Robert Klein (born February 8, 1942) is an American stand-up comedian and occasional actor.

His first major appearance was as host of the 1970 summer replacement television series Comedy Tonight, on which were introduced many of the routines that in the next few years would be released on record albums. His extensive routines about the Watergate scandal made him highly popular in the 1970s. He was one of the first observational comedians.

Klein appeared in several stand-up comedy specials on HBO dating to its very early broadcast days. He has traditionally concluded these shows with his "I can't stop my leg" routine.