There's only so many names out there so I suppose it's only natural that characters with the same name would pop up at different companies.

Banshee (Fox Features Syndicate 1940s? Fantastic Comics #21) Irish hero
Banshee (Marvel 1960s? X-Men) Irish mutant hero

The Black Cat (Harvey Publications 1941 Pocket Comics #1) Heroine
Black Cat (Marvel 1979 Amazing Spider-Man #194) Spider-Man villainess, reformed into hero.

Blockbuster (DC 1965 Detective Comics #345) Originally Mark Desmond who took a serum that gave him tremendous strength, but robbed him of his intellect. I think he was killed in the Legends miniseries, or maybe the early issues of Suicide Squad. His brother Roland became the second Blockbuster in Starman #1 1989.
Blockbuster (Marvel)

Borg (DC Comics, late `50s or early `60s, probably Mystery In Space) the bronze robot of Rann. Fought Adam Strange & the Justice League of America
The Borg (Paramount Pictures, Star Trek: The Next Generation) Collective of cyborgs that seek to assimilate all.

Captain Marvel (Fawcett Comics, later DC 1940 Whiz Comics #1) Billy Batson given the power to become Captain Marvel by saying the name of the old wizard Shazam.
Captain Marvel (M.F. Enterprises 1966 Captain Marvel #1) Robot with the power to split his body by saying Split & pull it back together by saying Xam.
Captain Marvel (Marvel Comics 1967 Marvel Super Heroes #12) Kree warrior Captain Mar-Vel comes to Earth to conquer it & ends up defending it.
Captain Marvel (Marvel Comics 1982) Policewoman given light-based powers, later called herself Photon
Captain Marvel (Marvel Comics) Son of Mar-Vel, originally called himself Legacy.
Captain Marvel (Marvel Comics 2004) Daughter of Mar-Vel

The Cat Man/Cat-Man/Catman (Holyoke Publishing 1940 Crash Comics #4) Hero
Cat-Man (DC 1963 Detective Comics #311) Batman villain

Daredevil (Lev Gleason/Comic House 1940 Silver Streak Comics #6) Hero, but now uses the name Reddevil
Daredevil (Marvel Comics Daredevil #1 April 1964) Blind hero.

Dr. Doome (DC 1940s? or 1950s?) Villain
Dr. Doom (Marvel 1960s Fantastic Four) Villain
Dr. Doom (M.F. Enterprises 1966 Captain Marvel Presents The Terrible 5 #1) Villain

Dr. Fate (DC 1940 More Fun Comics #55) hero
Dr. Fate (M.F. Enterprises 1966 Captain Marvel #2) villain

Dr. Hugo Strange (DC 1939? Detective Comics) Batman villain
Doc Strange (Better/Standard Publications 1940 Thrilling Comics #1) Dr. Hugo Strange gains superstrength from serum.
Doctor Strange (Marvel Comics 1963 Strange Tales #110) Master of the mystic arts

Dynamic Man (Marvel 1940 Mystic Comics #1)
Dynamic Man (Harry `A' Chesler 1941 Dynamic Comics #1)
Harry `A' Chesler was a book packager & his studio created both characters called Dynamic Man.

The Eye (Centaur Comics 1939 revived by Malibu Comics 1990s Keen Detective Funnies #16) Giant disembodied eye with a repulser ray that fought crime, in Malibu series The Protectors revealed to have a human form
The Eye (fanzine publication) Humanoid body topped with a giant eye.

Fatman (DC Batman #113) A circus clown who parodies Batman as part of his act.
Fatman, The Human Flying Saucer (Lightning Comics Fatman, The Human Flying Saucer #1-3 late `60s) Human given the power to turn into a living flying saucer who decides to fight crime.

The Fox (MLJ/Archie Comics 1939 or 40 Blue Ribbon Comics #4) hero
The Fox (DC Comics Detective Comics #253 March 1958) One of a trio of Batman villains

Hydroman (Eastern Color/Famous Funnies 1940 Heroic Comics #1) hero who could turn his body into water
Hydroman (Marvel) Spider-Man villain

Jack O'Lantern (DC 1982 DC Comics Presents #46) Hero
Jack O'Lantern (DC 1990 Justice League Europe Annual #1) Hero
Jack O'Lantern (DC 1982 Primal Force #0) Hero
Jack O'Lantern (Marvel) Spider-Man villain

The Mad Hatter (O. W. Comics 1946 The Mad Hatter #1) Hero
The Mad Hatter (DC 1948 Batman #49) Batman villain

Manhunter (Quality Comics early `40s)
Manhunter (DC early `40s Adventure Comics #73, revived & updated in the `70s) Game hunter Paul Kirk decides to hunt criminals instead. Later nearly killed & revived by an organization bent on ruling the world. Dies stopping them. Two good clones carried on the name. One of them died trying to stop Darkseid.
Manhunter (DC 1970s First Issue Special) Mark Shaw is recruited into the ancient order of assassins, the Manhunters.

The Mask (Better/Standard Publications 1940 Exciting Comics #1)
The Mask (Dark Horse Comics 1980s or 90s?)

Mr. E (Harry `A' Chesler 1940s Dynamic Comics #9)
Mr. E (DC 1980 Secrets Of Haunted House #31)

Nightshade (DC 1942 World's Finest Comics #6) villain
Nightshade (Charlton 1966 Captain Atom #82) heroine

Phoenix (Atlas 1970s Phoenix #1)
Phoenix (Marvel 1970s X-Men)

Plastic Man (Quality Comics 1941 Police Comics #1)
Plastic Man (M.F. Enterprises 1966 Captain Marvel #1?) Villain? Hero? from Venus

Quicksilver (Quality 1940 National Comics #5) Acrobatic superspeeder, hero, currently uses the name Max Mercury
Quicksilver (Marvel Comics early `60s X-Men?) Superspeeding mutant. Originally a villain, then a hero

The Raven (Ace Magazines 1940 Sure-Fire Comics #1) Hero
The Raven (Quality Comics 1940s Feature Comics #60) Hero
Raven (Tower Comics 1960s? T.H.U.N.D.E.R. Agents?) Hero
Raven (DC 1978 The Batman Family #19) Minor villain for Robin
Raven (DC 1980 DC Comics Presents #26) Hero, then villain

The Ray (Quality 1940 Smash Comics #14) hero
The Ray (M.F. Enterprises 1966 Captain Marvel) villain

Roy, the Super-Boy (MLJ/Archie 1940 Top-Notch Comics) non-powered sidekick to The Wizard.
Superboy (DC 1945 More Fun Comics #101)

The Shark (DC Comics Detective Comics #253 March 1958) One of a trio of Batman villains
The Shark (Image Comics 2000? Powers) Hero

Spider Woman (Harry `A' Chesler 1946 Major Victory Comics #1) Heroine
Spider-Woman (Marvel 1970s?)
Spider-Woman (Marvel 1980s? Secret Wars)

Tarantula (DC 1941 Star Spangled Comics #1)
The Tarantula (Atlas 1970s Weird Suspense Stories #1)

The Unknown Soldier (Ace Magazines 1941 Our Flag Comics #1) was turned into narrator of suspense stories & had named shortened to The Unknown in Four Favorites #21.
The Unknown Soldier (DC 1970 Star Spangled War Stories #151) Heroic soldier who used disguises

The Vulture (DC Comics Detective Comics #253 March 1958) One of a trio of Batman villains
The Vulture (Marvel Comics Amazing Spider-Man #2 May 1963 Spider-Man villain

Wildfire (Quality Comics 1940s Smash Comics #25) Heroine with fire powers
Wildfire (DC 1970s Superboy) Hero previously known as ERG-1, energy powers

The Wizard (MLJ/Archie 1939 Top-Notch Comics #1) Hero
The Wizard (DC 1947 All-Star Comics #34) Villain
The Wizard (Marvel 1960s? Fantastic Four?) Villain

Wonder Man (Fox Features Syndicate 1939 Wonder Comics #1) Superman knock-off
Wonderman (William H. Wise/Better Publications 1944 Mystery Comics #1) Hero
Wonder Man (Marvel 1960s? The Mighty Avengers)

Yellowjacket (Frank Communale Publishing Company 1944 Yellowjacket Comics #1)
Yellowjacket (Marvel 1970s? Avengers?) formerly Ant-Man/Giant-Man

Amazing Man (Centaur although later revived by Malibu Comics 1939 Amazing Man Comics #5)
Amazing Man (DC 1983 All-Star Squadron#23)
Amazing Man (DC 1994 Justice League America #86)
`Mazing Man (DC I think this humor series ran in the early `80s, but I can't find any info at the moment.)

In addition to the 2 Sharks listed above there was an earlier Shark (Centaur 1939 Amazing Man Comics #6) & I completely forgot about DC's most famous Shark, the villain who fought Green Lantern, Superman, Aquaman, the JLA, etc. (1963 Green Lantern #24)

Spy Smasher fought a villain called Mask, but I don't know if this happened during the Fawcett run or if it was written during the DC run.

Fantom Of The Fair (Centaur 1939 Amazing Mystery Funnies #11) hero, later changed name to Fantoman & was revived in the `90s by Malibu Comics
Phantom Of The Fair (DC 1986 Secret Origins #7) villain

`Mazing Man first appeared in `Mazing Man #1 1986.

Astra (Children's Press 1947 Zoom) Mystery air ace (Scottish publication)
Astra (DC 1950 Sensation Comics) Girl of the future

Ace Hart, the Atom Man (Foldes Press 1948 Superthriller)
Ace Hart (DCMT Ltd. 1953 Lone Star Magazine #1) After getting a notice from Foldes Press DCMT changed the name of their character to Space Ace with issue 3.

Wow. You and my step-father would get along so well.

Nemesis (American Comics Group 1967 Adventures Into The Unknown #154)
Nemesis (DC 1980 The Brave And The Bold #166)
Nemesis (DC 2000 JSA Annual #1)

Valkyrie (Hillman later revived by Eclipse 1942 Air Fighters Comics) girl fighter pilot
Valkyrie (Marvel 1970s? The Defenders?) superhero

Dr. Psycho (Centaur 1940? Amazing Man Comics #12) hero changed name to Dr. Hypno
Dr. Psycho (DC 1941? `42? Sensation Comics or Wonder Woman) villain

I believe Valkyrie debuted in the pages of The Avengers. She was most certainly a member of the Defenders.

Excelsior!

Unfortunately my Marvel reference book didn't list her, so I had to guess.

A quick check of the Grand Comic Book Database reveals that Valkyrie appeared in Incredible Hulk #142 before appearing in Defenders #4, her start with the (non-)team.

Excelsior!

Okay, flipping through my copies of Marvel Comics Index, it seems that Valkyrie debuted in Avengers #83. Her next appearance was Incredible Hulk #142, then she joined the Defenders. There. I feel better now, don't you?

Excelsior!

Yes. Thank you.

Iron Jaw (Lev Gleason Publications 1942 Boy Comics #1) Nazi villain
Ironjaw (Atlas 1975 Ironjaw #1) Barbarian... um, protagonist

Elasti-Girl (DC 1963 My Greatest Adventure #80)
Elastigirl (Disney/Pixar 2004 The Incredibles)

Was reading a thing on Aquaman villains & in Aquaman #36 (November-December 1967) appeared three villains Magneto, Torpedo & Claw.
I know Marvel has a Magneto (Uncanny X-Men #1 IIRC, but I'm not sure of the year) & I think they also have a Claw or is it Klaw, I think he's a master of sound.

Marvel also had a Torpedo. He was one of Daredevil's foes. Later, the Torpedo costume was taken over by someone else who became a superhero. (I think there may have been as many as three people who used the Torpedo costume. Talk about "one size fits all"...)

Excelsior!

I thought there might have been another Torpedo, but I couldn't find anything. Thanks.

The Torpedoes

Torpedo #1--appeared and killed in Daredevil #59, no relation to others

Torpedo #2--designed Torpedo suit, died

Torpedo #3--claimed suit and became superhero before dying

The Torpedo suit was eventually claimed by Turbo a.k.a. "Torpedo Sue."

The third Torpedo debuted in Marvel Premiere #39 (the story continued in the next issue). He next appeared in The Defenders around #60 (The issue where just about all of Marvel's second stringers showed up to apply for membership in the Defenders.) Later still, he appeared in the pages of ROM.

Excelsior!

Later still, he appeared in the pages of ROM.
A fate worse than death. ;-)

Thanks, guys.

There was also The Claw created by Jack Cole for Silver Streak Comics #1 in 1939 (Lev Gleason/Comic House). Villain could grow to monstrous size.

Moon Man (W. Forshaw 1946 Zip-Bang Comic) British spaceman superhero
Moonman (DC 1958 World's Finest Comics #98) Temporary super-powered villain

Skyman (Columbia 1940 Big Shot Comics #1) Costumed aviator hero
Skyman (DC 1980's Infinity, Inc.) Star-Spangled Kid with a new name

Firehair (Fiction House 1945 Rangers Comics #21) Red-haired woman raised by Indians (Dakotas)
Firehair (DC 1969 Showcase #85) Red-haired boy raised by Indians (Blackfoot)

Phantasmo (Dell 1940 The Funnies #45) Hero who fights crime in his astral form
Phantasmo (DC 1989 Young All-Stars #22) Half human/half elemental hero

How many old-time character names from other publishers did Roy Thomas reuse? Four that I'm sure of (Amazing Man, Phantom of the Fair, Phantasmo & Skyman), but I suspect more.

Ghost Rider (Magazine Enterprises 1949 Tim Holt #11) Cowboy Rex Fury dressed in glowing costume
Ghost Rider (Marvel 1967) Cowboy Carter Slade dressed in glowing costume, later renamed Night Rider
Ghost Rider (Marvel 1972 Marvel Spotlight #5) Demon-possessed biker with a flaming skull
Ghost Rider (Marvel 1990 Ghost Rider #1) Demon-possessed biker with a flaming skull

Atlas (Great Publications 1940s? Choice Comics #1) hero, given strength & agility from the god Atlas
Atlas (DC 1975 First Issue Special #1) Ancient hero

Blackout (Comic House Publications 1940 Captain Battle #1) Nazi-fighting wolflike scientist
Blackout (Holyoke 1940s Catman #10) Fighter pilot who fights crime at night

Black Widow (Marvel 1940 or `41 Mystic Comics #4) Works for Satan and kills those too evil to exist on Earth
Black Widow (Holyoke 1941 Catman Comics #1) Vigilante non-powered widow
Black Widow (Marvel 1960s) Russian spy turned superhero

Blue Streak (Holyoke 1940 Crash Comics #1) Hero who fights crime wearing a bullet-proof vest
Blue Streak (Prize Publications mid-40s Headline Comics #13) Crime-fighter

Bomber Burns (DC 1939 Detective Comics #27) Pilot with a heavily weaponed plane
Bomber Burns (Centaur 1941 Victory Comics #1) Pilot who fights Nazis

Cavalier (Better 1940 or `41 Thrilling Comics #7) Hero who dresses as a French cavalier
Cavalier (DC 1940s?) Batman villain who dresses as a cavalier

Chameleon (Funnies, Inc. 1940 or `41 Target Comics #6) Heroic master of disguise
Chameleon (Marvel 1963 Amazing Spider-Man #1) Villainous master of disguise
Chameleon (DC 1990s?) Formerly Chameleon Boy of the Legion of Super-Heroes

Cyclone (Quality 1940 National Comics #1) Hero of the year 3000
Cyclone (Nita Publication 1940 Whirlwind #1) Hero who uses jui-jitsu, athletics & acrobatics to fight crime

Iron Munro (Street & Smith 1940? Army & Navy Comics #1) Interplanetary adventurer
Iron Munro (DC 1987 Young All-Stars #1) Post-Crisis Superman replacement
That makes 5 names, so far, that Roy Thomas has recycled from other companies.

Another villainous Doctor Doom appeared in 1940 in Big 3 #1 (Fox Features Syndicate)

Dan Hastings (Centaur late 1930s or 1940 Amazing Mystery Funnies Volume 2 #4) Futuristic spaceman
Dan Hastings (Harry `A' Chesler 1940s Dynamic Comics #8) Futuristic spaceman

Destiny (Quality 1940s Police Comics #15) Crimebuster
Destiny (DC 1972 Weird Mystery Tales #1) Horror comic host, later one of the Endless

Electro (Marvel February 1940 Marvel Mystery Comics #4) Heroic robot
Electro (Fox Features Syndicate February 1940 Science Comics #1) Hero, changed name to Dynamo with second appearance
Electro (Marvel 1954 Captain America) Electrically-charged communist villain
Electro (Marvel 1964 Amazing Spider-Man #9) Electrically-charged crook

Falcon (Archie 1940 Pep Comics #1) Non-powered hero
Falcon (Marvel 1940 Human Torch Comics #2) Non-powered hero

Ferret (Marvel 1940 Marvel Mystery Comics #4) Non-powered hero with a trained ferret
Ferret (Centaur 1942 Man Of War Comics #2) Flying vigilante with superstrength
Ferret (Malibu 1990s The Protectors #1) The name & secret identity was taken from the Centaur version, but they remade the guy as a Wolverine-type

Fighting Yank (Better Publications 1940s Startling Comics #10) Wears cloak that gives him superstrength & invulnerability & assisted by the ghost of his ancester
Fighting Yank (Marvel early 1940s Captain America Comics #6) Non-powered fighter

Firebrand (Quality 1941 Police Comics #1) Non-powered hero
Firebrand (Family/Harvey 1943 All New Comics #1) Hero with electrical powers, superstrength, glows in the dark & has a force field
Firebrand (DC 1982 All-Star Squadron #5) Fire-weilding heroine, sister of first Firebrand
Firebrand (DC 1996 Firebrand #1) Hero with fire powers

Flame (Fox Features Syndicate 1939 Wonderworld #3) Fire-based hero
Flame (Spark Publications 1946 Golden Lad #5) Non-powered female sidekick of Shaman

Sandman (DC 1939 Adventure Comics #40) Hero who fights crime originally with a knockout gas, then with a wirepoon gun & Sandy the Golden Boy
Sandman (Marvel 1963 Amazing Spider-Man #4) Villain with sand-based powers
Sandman (DC 1974 Sandman #1) Hero of the dream plane
Sandman (DC 1980s? Infinity, Inc.?) Formally Silver Scarab, took over as hero of the dream plane, later became new Doctor Fate
Sandman (DC 1989 Sandman #1) Morpheus, lord of dreams

Another Wonder Man, a revived mummy named Mystico in Startling #1 (Better Publications).

Black Fury (Fox Features Syndicate 1940 or `41Fantastic Comics #17) Crimefighting gossip columnist
Black Fury (Street & Smith 1941 Super Magician Comics #1) Gliding jungle hero originally called just Rex King, but later took on identity of Black Fury

Creeper (Marvel 1942? Krazy Komics #1?) Villainous funny animal
Creeper (DC 1968 Showcase #73) wildly dressed hero

Dagar (Fox Features Syndicate 1940s All-Great Comics #13) Tarzan clone who works in the desert
Dagar (Gold Key 1972 Dagar The Invincible #1) Barbarian hero (According to creator Don Glut the name was supposed to be Daggar, but the editor shortened it to Dagar. Neither knew of the 1940s character)

Dan Dare (Fawcett 1940 Whiz Comics #2) Private eye
Dan Dare (some English comic) Pilot of the future

The Gargoyle (Holyoke 1940s? Captain Aero #4) Hero who fights crime in top hat & tails
Gargoyle (Marvel 1970s? Defenders?) Hero who looks like a gargoyle

The Ghost (Lev Gleason 1940s Daredevil Comics #5) Fighter pilot
Ghost (Dark Horse 1993 Comics Greatest World) Crimefighting ghost

Golden Girl (Spark 1946 Golden Lad #5) Sidekick for Golden Lad
Golden Girl (Marvel 1948 Captain America #66) Sidekick for Captain America

Hercules (Quality 1940 Hit Comics #1) Superstrong hero
Hercules (Marvel 1940s Mystic Comics #3) A giant superstrong genius
Note: The mythological character Hercules has also been used in Archie, DC & Marvel & probably others, but since mythological beings are public domain I don't plan on listing them.

Immortal Man (Street & Smith 1944 Red Dragon #9) 100,00 year old caveman
Immortal Man (DC 1965 Strange Adventures #177) 50,000 year old caveman

Johnny Rebel (Dynamic 1941 Yankee Comics #2) Southern crimefighter
Johnny Rebel (Family/Harvey 1943 All-New Comics #1) Southern crimefighter

King (DC 1940 Flash Comics #3) Master of disguise who fights crime
King (Centaur 1940 The Arrow #1) Adventurer & detective who fights crime

Lance (Harry `A' Chesler 1944 Bulls-Eye Comics #11) Non-powered sidekick of the Green Knight
Lance (Ace 1940s Captain Courageous Comics #6) Super-powered sidekick of the Sword

Lucky Coyne (Archie 1939 Top-Notch Comics #1) Detective who uses identity of Bat Yardly to capture crooks
Lucky Coyne (Harry `A' Chesler 1941 Dynamic Comics #1) Detective who flips a coin to make decisions

Wasp (Lev Gleason 1939 Silver Streak Comics #1) Male crimefighter
The Wasp (Marvel 1963 Tales To Astonish #44) Female crimefighter

Wonder Boy (Funnies, Inc. 1940 Blue Bolt #1) Superpowered boy
Wonder Boy (Quality 1940 National comics #1) Superstrong alien

Yankee Girl (Four Star Publications 1945 Captain Flight #8)
Yankee Girl (Harry `A' Chesler 1947 Dynamic Comics #23)

Black Orchid (Family/Harvey 1943 All New Comics #2) Non-powered costumed crimefighter
Black Orchid (DC 1973 Adventure Comics #428) Mysterious crimefighter

Black Panther (Centaur 1941 Stars And Stripes #3) Non-powered fighter
Black Panther (Marvel 1960s Fantastic Four #52)

Captain Thunder (Fawcett 1939 Flash Comics Ashcan Edition) Original name for Captain Marvel
Captain Thunder (Fiction House 1940s? Jungle Comics #1) Leader of the Congo Lancers in Africa
Captain Thunder (DC 1970s) Apparently some kind of Captain Marvel stand-in DC used.

The Clown (Harvey 1941 Spitfire Comics #1) Crimefighter disguised as a clown
The Clown (Marvel 1965 Amazing Spider-Man #22) Criminal clown

Marksman (Quality 1942 Smash Comics #33)
Marksman (Centaur 1941 or 42 Amazing Man #23)

Masked Marvel (Centaur 1939 Keen Detective Funnies Volume 2 #7) Masked crimefighter
Masked Marvel (Youthful 1940s? Gunsmoke #1) Old west masked crimefighter

Miss America (Quality 1941 Military Comics #1) Granted powers by the Statue of Liberty
Miss America (Marvel 1940s Marvel Mystery Comics #49) Given powers by a lightning bolt

The Phantom Eagle (Fawcett 1940s Wow Comics #6) fighter pilot
Phantom Eagle (Marvel 1960s or 70s) Not sure, saw a reference to him in a Marvel Checklist

Power Man (Fiction House 1940s? Fight #3) Wears a magic red jacket which gives him superpowers to fight crime
Powerman (Cartoon Art Productions? 1940s? Super Duper Comics #3) An Englishman in America given powers by a ghost
Powerman (DC 1950s or 60s World's Finest Comics) A robot used by Superman once
Power Man (Marvel) Villain, changed name after fight with Luke Cage
Power Man (Marvel) Luke Cage

Prankster (Rural Home 1945 Red Circle Comics #1) Hero who fights with magic props
Prankster (DC 1942 Action Comics #51) Villain who uses pranks to commit crimes

Ragman (Holyoke 1941 Catman #1) Crimefighter disguised as a derelict
Ragman (DC 1976 Ragman #1) Crimefighter with the strength of six winos

Red Hawk (Marvel 1943 or 44 Kid Komics #3) Plane flown by American fighter pilot
Red Hawk (Enwill Publishing 1944 Blazing Comics #1) Indian fighter pilot

Rick O'Shay (Fawcett 1940 Master Comics #1) Adventurer & mercenary
Rick O'Shay (Chicago Tribune-New York News Syndicate 1958 Rick O'Shay comic strip) Humorous western lawman

Sally Forth Wally Wood heroine who keeps losing her clothes
Sally Forth Comic strip wife & mother who keeps her clothes on

Sky Wolf (Lev Gleason 1940? Silver Streak Comics #4) Fighter pilot
Skywolf (Hillman 1942? Air Fighters Comics #2) Fighter pilot who wears a wolf head for a hat

Spitfire (Quality 1940 or 41 Crack Comics #15) Fighter pilot
Spitfire (John F. Mahon 1941 Spitfire Comics #1) A sailor who slept for 2 centuries on a volcanic island to discover he can breathe fire, poison gas & fog

Sword (Quality 1940s Smash Comics #24) Non-powered crimefighter with a sword
Sword (Ace 1940s? Captain Courageous Comics #6) Superstrong crimefighter who gets powers from Excalibur

Tor (Quality 1940 Crack Comics #10) Magician crimefighter
Tor (Joe Kubert 1950s Tor #1?) Caveman

The Voice (Dell early 1940s Popular Comics #53) Police detective wearing suit of invisibility
The Voice (Centaur 1941? Amazing Man Comics #22) Crimefighter who uses ventriloquism & circus tricks

Phantom Eagle (Marvel 1960s or 70s) Not sure, saw a reference to him in a Marvel Checklist

I'm not sure, but I seem to recall that he was a member of a retconned WWI superhero group recalled in a quick flashback scene when one of the other members (the Original Union Jack?) met the Invaders.

The Grand Comic Book Database (a superb online comics reference resource) lists an appearance by the Phantom Eagle in Incredible Hulk #135. He also appeared in Marvel Super-Heroes #16 (thought that's where I'd seen him) and Ghost Rider #12.

Excelsior!

What's interesting is that the term Phantom Eagle doesn't seem in any way generic (like Clown or Ghost) so the idea that two different comic companies could independently create characters with the same name seems unlikely.

Be interesting to learn the story behind the story.

Nightman (DC 1960s? World's Finest Comics #155) Batman replacement
Nightman (Malibu 1990s NightMan #1) Superhero saxplayer

The Phantom (King Features 1936 The Phantom comic strip) A family of crime fighters
The Phantom (Marvel 1965 Tales Of Suspense #63) Disgruntled employee/saboteur

Marvel also had a Tarantula (2 apparently).

Gog (Marvel 1971 Amazing Spider-Man #103) Giant alien lackey of Kraven the Hunter
Gog (DC 1998 Gog #1) Lunatic time traveler/killer of Superman

Knockout (Marvel 1990 Amazing Spider-Man #340)
Knockout (DC 1994 Superboy vol 3 #2)

Captain Power (Syndicated TV Show 1987 Captain Power And The Soldiers Of The Future) TV show hero
Captain Power (Marvel 2000 Amazing Spider-Man #10 volume 2) Radiation-powered shapeshifting villain

Midnight (Quality 1941 Smash Comics #18) heroic masked man
Midnight (Marvel 1970s? Moon Knight?) heroic sidekick who became villainous cyborg

Shade (DC 1942 Flash Comics #35) villain who uses a dark projecting cane
Shade (Marvel 2001 Amazing Spider-Man #40 v2) villain who can transport others to the astral plane so he can once again walk Earth

Sin-Eater (Marvel 1980s one of the Spider-Man books) Insane killer
Sin-Eater (DC 2001 JSA #23) Thanagaran devil

The Cobra (Ace Comics 1940s Super-Mystery Comics?) villain
The Cobra (Marvel Comics 1960s Journey Into Mystery?) villain

The Vulture (MLJ 1940s Pep Comics?)
The Vulture (Marvel 1960s Amazing Spider-Man #2)

The Demon (Marvel 1960s Strange Tales #128) villain
The Demon (DC 1972 The Demon #1) hero

Dynaman (Timely 1940s Daring Mystery Comics #6) Hero
Dyna-Man (DC 1966 Metamorpho #8) False identity Metamorpho uses to infiltrate a criminal gang

The Thunderer (Timely 1940s All-Winners #6) Hero
The Thunderer (DC 1967 Metamorpho #14) Villain

Shadowman (DC 1962 Superboy #101)
Shadowman (Valiant 1992 Shadowman #1)

Sunspot (DC 1981 The Legion Of Super-Heroes #272) Heroine
Sunspot (Marvel 1982 Marvel Graphic Novel #4) Hero

El Diablo (DC July 1938 New Adventure Comics #28) Villain
El Diablo (Fawcett June 1943 Master Comics #39) Villain
El Diablo (Marvel April 1955 Sub-Mariner Comics #39) Villain
El Diablo (DC October-November 1970 All-Star Western #2) Hero
El Diablo (DC August 1989 El Diablo #1) Hero

Here's a list of over 400 names that Marvel & DC have used.

The Cat Man/Cat-Man/Catman (Holyoke Publishing 1940 Crash Comics #4) Hero
Cat-Man (DC 1963 Detective Comics #311) Batman villain
And predating them was
The Catman (Centaur 1939 Amazing Man Comics #5) - Hero?

Black Mask (Quality 1940 Feature Comics #34) - Villain
Black Mask (Lev Gleason 1942 Silver Streak Comics #18) - Heroine
Black Mask (O. W. Comics 1946 The Mad Hatter #1) - Gang Leader
Black Mask (Aviation Press 1945 Contact Comics #8) - Villain
Black Mask (Fiction House 1950 Jumbo Comics #140) - Villain
Black Mask (Marvel 1962 Kid Colt Outlaw # 106) - ?
Black Mask (DC 1985 Batman #386) - Villain

Dr. Psycho (Centaur 1940? Amazing Man Comics #12) hero changed name to Dr. Hypno
Dr. Psycho (DC 1941? '42? Sensation Comics or Wonder Woman) villain
And that turns out to have been wrong. Dr. Hypno was never known as Dr. Psycho.


The Gargoyle (Holyoke 1940s? Captain Aero #4) Hero who fights crime in top hat & tails
Gargoyle (Marvel 1970s? Defenders?) Hero who looks like a gargoyle
And like Black Mask, Gargoyle seems to have been a fairly common name. A search turns up a bunch at the Grand Comic Database, although which were actual characters using the name & which were somekinda animated waterspouts isn't specified.

Gargoyle (O. W. Comics 1946 The Mad Hatter #2) crook who had his brain transplanted into a gorilla's body then uses rubber masks to hide his gorilla face.

Spider Woman (Harry `A' Chesler 1946 Major Victory Comics #1) Heroine
Spider-Woman (Marvel 1970s?)
Spider-Woman (Marvel 1980s? Secret Wars)
Spider Woman (Eastern Color 1943 Heroic Comics #21) Villainess
Also I think Marvel added a third Spider-Woman during Byrne's time on Spider-Man

The Spectre (DC Comics February 1940 More Fun Comics #52) Avenging ghost hero.
The Spectre (Dell Comics May 1941 Crackajack Funnies #35) Criminal mastermind.