This is probably because every role he’s ever played, everyone always says “Wait, that was Gary Oldman?”.
Agreed. Philip Seymour Hoffman is one of our greatest actors and did a wonderful job playing Truman Capote, but Toby Jones was Truman Capote.
My kids are 11, 5 and 2.
Chris Tucker should have won Best Supporting Actor for playing Ruby Rhod in The Fifth Element. Absolutely masterful comedic performance.
How about James Earl Jones for his voice work in the Star Wars movies? I know it’s only voice work, but it was masterful, iconic, enduring and he gets a huge level of difficulty for having to work with Lucas’ terrible dialogue.
Irvin Kirschner for directing The Empire Strikes Back.
Now we know how bad Lucas can be, it’s amazing how great the talented people that overrode him were. Kirsch deserves credit for making the best movie of the 1980’s, in my opinion(Empire, not Robocop 2). 
I just watched Saving Private Ryan again (the wife had never seen it), and it reminded me of how great an actor Giovanni Ribisi is. Especially in this scene.
The youtube link contains spoilers for those who haven’t seen the film.
John Cazale and Gary Oldman, already mentioned, are the correct answers.
Since voice work has been suggested, Andy Serkis in Lord of the Rings: The Two Towers.
Robert Shaw as Quint. I mean, how perfect do you have to be?
"Anti shark cage? You go in the cage? Cage goes in the water? You go in the water? Shark’s in the water?
Farewell and adieu to you, fair Spanish ladies…"
Once again, I’ll ignore specific performances and note that the following actors and actresses have NEVER received a single Academy Award nomination. Mind you, I’m not complaining that they were snubbed for this or that worthy performance. I’m saying that NONE of their perfomances has EVER been honored with a measly nomination:
The aforementioned Edward G. Robinson
Donald Sutherland
Alan Ladd (not even for “Shane”)
Maureen O’Hara
Errol Flynn
Myrna Loy
Peter Lorre
Bruce Willis
Richard Gere
Boris Karloff
Bela Lugosi
(I was all set to say Fred Astaire, but then remembered he got a sort of lifetime achievement nomination for “The Towering Inferno”)
Other people had already mentioned Marilyn Monroe and Jim Carrey
Incidentally, it isn’t just actors who’ve been snubbed. The following DIRECTORS never received a single nomination as Best Director:
Christopher Nolan
Spike Lee
Sam Peckinpah
ISTR that after either *The Truman Show *or *Man in the Moon * (I can’t remember which) Carrey went off on a rant about the Academy. I personally suspect that if he’d kept his mouth shut he might have gotten at least a nomination for Eternal Sunshine, but the Academy bods are a touchy bunch.
He MAY have done a rant that I’m not aware of, but I recall that he was a presenter of a minor award the year “The Truman Show” came out. He did a very funny bit in which he PRETENDED to be bitter and heartbroken.
Then he calmed down and said aloud, “That’s all right, I’m fine. After all, it’s an honor just to be nomin…”
Then, as if he’d just realized he hadn’t been nominated, he broke into a fake bawl.
It was only a joke, and I thought everyone appreciated it.
I forgot one…
Do you think Alec Baldwin can EVER set foot in a Starbucks again without someone telling him, “Put that coffee down- coffee is for CLOSERS only.”
Seriously, in a movie with a stellar cast, in which EVERYBODY gave an Oscar-worthy performance, Alec Baldwin completely dominated “Glengarry Glen Ross” with a scene that couldn’t have lasted more than a few minutes.
“Fuck you, THAT’S my name!”
“Nice guy? I don’t give a shit. Good father? Fuck you, go home and play with your kids. You wanna work here? CLOSE!”
Alec should have won the Oscar as Best Supporting Actor (though the actual winner, Gene Hackman in “Unforgiven,” was excellent, too). He wasn’t even nominated.
Christian was born in Wales, but he’s not Welsh. His parents are English and he was raised in London and Los Angeles.
To me, the whole BAFTA lovefest for The King’s Speech was inevitable–it’s a bigger hit and is getting more recognition over there then here, which is why Rush and Bonham-Carter won. I think Bale and Leo are still the Oscar favorites, which I think is fantastic particularly for Bale.*
On that note, I agree with that he should have got recognition for American Psycho and at least a nomination for Empire of the Sun.
*I did enjoy TKS very much, and thought everyone did great.
I know this board is split down the middle when it comes to Napoleon Dynamite but Jon Heder created an iconic character out of thin air (or based on who knows who from his life) and was amazing. I’ve seen him in other roles since and he seems to play himself which is totally different than the Napoleon character.