I would call Carson a wit, and the others comedians. That is, when he interviewed someone, he came up with a lot of funny ad lib reactions. (Actually, Paul Lynde was also a wit, on Hollywood squares, but he had those replies pre-written for him.)
@DrWatson True but he also got invited to parties for his ongoing commentaries. He was on the social "A" list until the booze just turned him into a complete psycho.