Though Kevin Spacey was the 'Late Night' (weeknights, 12:37AM ET on NBC) guest, Jimmy Fallon seemed more interested in watching the actor be other people -- namely Johnny Carson, and a bit of Jack Lemmon. Well, he is very good at it...

Spacey obliged, swapping seats with the host. "Jimmy, how the hell are ya?" he asked Fallon in pitch-perfect Carson tones. "Do you enjoy doing the show every night, is it fun?" Fallon answered, "We have a lot of fun guests, talented guests, like the great actor Kevin Spacey."

"Monologues can be tough, though, can't they?" said Spacey/Carson. "I just like sitting here watching you suffer."