Is this a compliment or an insult? I think I’ve heard it as both. (Most recently, negative and used in this thread.) What does it mean?
I take it to mean “ferocious overacting that stops just short of foaming at the mouth.” Lots of yelling and grand gestures and fierce facial expressions and throwing things and knocking things over. Basically it implies that the actor did everything BUT take a bite out of the scenery.
See Tim Roth’s performance in the Planet of the Apes remake. Or Brian Blessed as Augustus in I, Claudius. And pretty much everyone on Dynasty. Sometimes it really works as part of the character - Peter O’Toole in The Lion in Winter. Sometimes it’s terrible - William Shatner trying to express strong anger or really any strong emotion is a frightening thing to behold.
Insult. It means that the actor is going completely over the top, using extreme tones, actions, and body motions to get the message across that they’re upset about something. Charleton Heston did this. William Shatner is godlike in his scenery-chewing, but neither of them compare to Jeremy Irons in Dungeons and Dragons. The real reason they did the entire castle in CGI was that after the first day of shooting, there was nothing left but splinters in his mouth.
Oh my god, yes. It got hilarious, after a while. There’s a deleted scene where you see him yelling and waving his arms around, and then the director yells “Cut!” and Jeremy just stops and stalks off to his trailer, no doubt for another round of punching his agent in the gut.
Also, see Gene Hackman in nearly anything he’s been in. Sometimes it works.
Al Pacino is another one famous for it - think of just about any movie where he starts yelling and lurching all over the place.
You mean “You Klingon bastards” where he misses the chair, or “Don’t mince words, Bones, what do you really think?”
Olivier in just about anything. Especially after 1970, when he was building up a nestegg for his kids.
I’ve never thought of Hackman as someone who overacts. Maybe in Superman. But The Conversation? Unforgiven? Hoosiers? Young Frankenstein??? 
Hey, Ellen, don’t point that quote at me! That was Legomancer!
Scenery chewing can be great in the right kind of movie. I can think of two right off:
2nd prize goes to Jack Nicholson in Batman. Dancing around while he’s shooting Jack Palance, laughing maniacally, it works.
The best job of appropriate scenery chewage was John Lithgow in The Adventures of Buckaroo Bonzai Across the 8th Dimension. Bad teeth, stooped posture, hair going every direction at once and muttering to himself in a bad Italian accent. I still laugh every time I see it.
Sid Haig, in “Jason of Star Command,” was the most impressive example of overacting I’ve ever seen. When he got angry, you could almost see smoke coming out of his ears (without special effects).
This reminds me of a friend who commented, “The ultimate Oscar-winning movie would have Al Pacino shouting at a crying Meryl Streep.”
Gary Oldman gets a fair amount of his sustenance from scenery as well. “Dracula,” “Lost in Space,” “Hannibal,” and “The Fifth Element” provide wonderful examples.
Someone mentioned the king of scenery-chewing in an earlier posts - Charlton Heston. Except in his case, I get the impression that he’s like this all the time. The glue from his rug has eaten into his brain, I think. I saw a clip of him speaking before the NRA and he actually seemed to be playing Moses all over again.
I feel it necessary to point out what I believe to be one of the greatest scenery chewing displays ever.
wait for it…
Anthony Hopkins in Legends of the Fall.
somehow he manages to chew scenery while being unable to speak coherently
I’d like to offer an example of someone who is more of a scenery nibbler: John Malkovich. When that guy goes off, it’s like watching a controlled burn in a national park. I imagine that when the director yells “cut,” that’s when Malkovich trashes the set.
Whoever got the bright idea to put him up against Willem Dafoe in Shadow of the Vampire should be given the highest praise.
(I saw Legends of the Fall for a buck and a half once, and it still pisses me off. That’s neither here nor there, but I just had to say it.)