-Batman. The ball. Batman Forever

etc.

Spock arriving at the Enterprise (the ship and the actual enterance). - Star Trek: The Motion Picture

Kirk's entrance in "Star Trek II." ("Alright, open her up.")

Norman Bates's "Mother" in i{Psycho}.

When we first meet Joliet Jake (John Belushi) in Blues Brothers.

Chevy Chase that movie with Golidie Hawn when he first left SNL.

Jessica Rabbit, "Who Framed Roger Rabbit?"

Ursula Andress, "Dr. No"

Leslie Nielsen in the first two "Naked Gun" films.

Dark Helmet in Spaceballs.
"I can't breath in this thing!" (approx)

Chestbuster in Alien.

Kenneth Brannagh's first appearance in Henry V, silhouetted in the doorway.

Alan Rickman in Harry Potter, Dogma, and Die Hard.

Jason Mewes and Kevin Smith in Dogma, Chasing Amy, and Clerks.

Darth Vader in A New Hope & Return of the Jedi.

The Borg Queen in First Contact

C***knocker in Jay & Silent Bob Strike Back ("Hey Kids! It's Mark Hamill! [appluase]").

Nicole Kidman in "The Others"

John Doe in Se7en: "You're looking for me..." Man, I get chills....

The Terminator in T2: Specifically when he walks out of the elevator in the mental home, there's that weird bell-ringing in the background and Sarah stops in her tracks.

Cpatain Jack Sparrow from Pirates of the Carribean
sinking into port.

Darth Vader - "Star Wars" (previously mentioned)

Indiana Jones - "Raiders of the Lost Ark" (when we first see his face, after he uses his bullwhip to disarm the guy who draws a gun on him from behind)

Mr. Stay Puft - "Ghostbuster" (think about it; I bet you can hear the footsteps right now)