Another Meryl Streep one - a lot of fancy camera work, heels and nifty set design in “Julie and Julia” to add the required 8 inches to bring Meryl (5’ 6") up to Julia’s level (6’2").
The CGI work to create “weedy Steve” for Captain America.
Elf. All the elfs are normal sized humans.
Not quite what the OP had in mind, but…way back when, when they made Final Fantasy: The Spirits Within, apparently (from what I remember on the DVD commentary) they used a notably bulkier man than the character when doing the motion-capture acting for one of the villains, General Hein (the voice was done by James Woods).
The result was that the rendered character ended up moving with more of a heavy swagger than expected, which actually looked better than most of the other humans did. (I know, faint praise, but… 
)
What about Verner Ölund aka Warner Oland as Charlie Chan?
Christian Slater as WW2 Winston Churchill
Pretty sure you mean Anthony Hopkins.
That’s kinda the whole point of the thread.
For a few people, Phillip Seymour Hoffman was casting magic as Art Howe, despite the two being physical opposites in almost every way. I wasn’t casting magic for me–I thought it was a terrible choice–but some friends have disagreed.
I never saw it but Jonathan Rhys Meyers was supposed to be mesmerising in The Tudors as Henry VIII. He didn’t look even a little bit like Henry VIII though.
How about Chevy Chase as Gerald Ford in those early SNL years?
Alan Ladd was 5’6". Pretty much every male actor he played against was taller than him (Jack Palance was 6’4" in Shane, Robert Preston was 5’10" in Whispering Smith, etc.) It’s a good thing Ladd had the 4’11" Veronica Lake to be a leading lady.
It is? Nothing about Wolverine in the X-Men movies called for a short guy. The character has historically been portrayed as short (but the 90s X-Men cartoon ignored this trait long before the movies were conceived), but that’s the comics.
The rest of this thread has been X (who is tall) played Y (who is shown to be short) or vice versa.
A friend of mine worked as a stuntwoman on GalaxyQuest. She said that the flat-chested Sigourney Weaver was utterly amused, and thrilled, to finally have breasts, thanks to cunning wardrobe tricks.
Gary Sinise, of course, has two legs in real life. But he played a double amputee in Forrest Gump. It was done mostly with CGI - Sinise wore green leggings on his lower legs and they were editing out of the shots.
But there was one shot that was subtle enough most people didn’t even think about it. Sinise was sitting on a railing and he spun around 180 degrees. On screen, Sinise’s knees passed over the top railing but in real life, his lower legs would have hit the fence.
The shot was done with CGI. They cut out the section of the fence and Sinise spun around and his legs passed through the gap. They then edited out his legs and edited in the missing section of the fence for the on-screen shot.
In that clip I noticed Mia Sara. Who was eighteen at the time, phew.
From Marvel’s page on Wolverine:
From the OP:
OK, so I just Googled up a story I was vaguely remembering. In the 1957 movie Boy on a Dolphin, the diminutive Ladd starred alongside the taller Sophia Loren. Apparently, to avoid having her tower over him, some tricks were required during filming:
[QUOTE=Wiki]
The disparity in heights between the 5 ft 8 in (1.73 m) Loren and 5 ft 6 in (1.68 m) Ladd led to complications in filming. Some of their scenes together required him to stand on a box, while another forced a trench to be dug for Loren when the pair walked along the beach.
[/QUOTE]
I don’t know why I find that mental image so funny…
Assuming that cases where the size of the character was changed to match the actor (e.g., Wolverine) count, then Brian Dennehy winning an Tony for playing Willy Loman is a great example. The character’s name even hints at his size in stature and life.
However, I think the spirit of the op are cases like Gimli or Aileen Wuornos where the apparent size/looks of the actor were made to match the character.
There are also cases Benjamin Buttons and the Nutty Professor where the character goes through drastic physical changes while being played by the same actor.
Yeah, but the rest of the OP makes it pretty clear that he’s talking about actors who actually appear taller or shorter onscreen. Not that the thread hasn’t drifted since then.
You know Vasquez, the tough muscly hispanic space marine in Aliens? Here’sher actress.
That, of course, is the 1952 movie Moulin Rouge. In the 2001 movie of the same title, John Leguizamo played the role. (again on his knees in some scenes)