(This is a contribution to the Close-Up Blog-a-thon sponsored by The House Next Door.)
There are a lot of ways to consider great acting, and as far as I'm concerned one of the best at what he did was Vincent Price in dozens of sci-fi and horror movies for five decades. If the minimalistic, emotionally grounded Method approach of someone like Marlon Brando is filet mignon, then Vincent Price is a slightly greasy hamburger - you know it's not really good for you, but damn if it isn't still pretty damn good. Price raised ham to the level of fine art.
The best vehicle for Price's acting range in a single movie is probably Roger Corman's Pit and the Pendulum (spoilers from here). Price is Nicholas Medina, a tremulous man scarred after a lifetime of living in the same cavernous castle filled with torture implements, Nicholas's father having been part of the Spanish Inquisition. For most of the movie, Price is in full-blown Poe anguish mode, tormented about the possibility that his recently dead wife (Barbara Steele) might have been buried alive. This is how Nicholas looks for most of the movie:
Note that even Price's 'pathos' is at at least 8 or 9 while everyone else in the movie has their performance scaled around 5.
As it turns out, Nicholas has reason to be nervous, because his wife has faked her own death as part of an elaborate scheme to drive Nicholas crazy and steal his fortune. After Barbara Steele emerges from her tomb and chases Nicholas around the castle for a bit, he's basically catatonic. But after the reality of the deception sinks in (with the help of a little added taunting from his wife), Nicholas's demeanor changes dramatically, which Corman shows in a single, uncut shot:
It's like watching the Grinch's heart expand three sizes. That supple transition from terrified and cowed into malevolent, purposeful, and joyously vengeful is the real climax of the story for me. This is Nicholas for the rest of the movie, and the way I like my Vincent Price: a magnificent, silky villain, bigger than life but under complete control of his face and voice.