And that grin! “Who, me?” Ye gods!
Ned Beatty Network
When Harrison Ford finally shows his face in Raiders of the Lost Ark, you immediately knew this was a man who knew his shit.
The Jurassic Park main gate.
Well, I thought it was a pretty impressive entrance.
Just after that video ends, Bond has to take a phone call. Striding across the room to the strains of that theme, he makes even a chat on the phone look like the most damnedest cool thing to do 
The Balrog.
Nothing else comes close.
Since I didn’t click on any of the links, I may be repeating something posted by someone else, for which I apologize in advance:
Omar Sharif’s first appearance in Lawrence of Arabia.
Apparently he has regretted ever since that he was not actually riding the camel for the whole sequence.
If I might include the small screen, and extrapolate “entrance” to include a long-absent character’s return to a series…
… then Giles’ appearance in the final seconds of “Two to Go,” in Buffy’s season 6, is the hands-down winner.
First thing I thought of, and you posted while I was out looking for a clip. (about 2 minutes in)
I’d vote instead for his entrance in For A Few Dollars More. Walking towards the saloon from the back, then a sudden downpour, then he light his cigar under his hat, then he looks up into the camera right when a thunder clap happens. (Which is ruined on my DVD copy b/c the sound is off and the thunder happens early)
Bogart’s first appearance in Casablanca. Tracking the cigarette up to his mouth.
Mary Poppins floating down from the skies with her umbrella unfurled.
Since I already mentioned Superman, I’ll also throw in Batman’s entrance from the first Tim Burton Batman movie.
“Don’t kill me, man! Don’t kill me!”
“I’m not going to kill you. I want you to do me a favor. I want you to tell all of your friends about me.”
“What are you?!”
…
“I’m Batman.”
If we’re going to do TV re-entrances, I’m going to add Isaac’s return in *Sports Night * (Robert Guillame had suffered a stroke, so they had Isaac suffer one too. Then he came back right after Dana broke up with Gordon and she’s having a meltdown.)
Ouch.
I can do better than that from a TV show. in fact, I can do better than that from an Aaron Sorkin TV show.
In the first episode of The West Wing, everyone has been in a tizzy; not least because the President has fallen off his mountain bike. And the representative of some religious group has said some things on TV about one of his daughters, which all the staffers know will earn his wrath. The President is the driving force for all events, but we haven’t seen him yet. Toby has the leaders of the group in to discuss matters with them, and the conversation turns toward commandments; they can’t agree on which one is first. As the argument starts to get heated, Martin Sheen comes through the door, in full bluster, and says “I am the Lord, thy God, you shall have no other Gods before me!”
Now, that’s an entrance.
I won’t bother reading the rest of the thread, because it has to be 50 or so more posts agreeing with this one.
If the small screen is eligible, I’m going to rank the top three Doctor Who regenerations:
- Christopher Eccleston goes up in flames, and morphs into David Tennant
- Tom Baker dissolves into Peter Davidson (“The moment has been prepared for”)
- Davidson lays down his life for Peri, then sits up as Colin Baker (“You were expecting someone else?”)
Darth Vader was good, but Rick Moranis’s Dark Helmet in Spaceballs was better!
I was in a theater watching a remastered version with about 100 other people. When she hit the screen there everyone gasped. Man, woman and child. It was actually a deafening gasp.
She was amazing.
OMG, how have I never noticed before that he’s wearing a friggin’ tie?!