Clark Gesner (born March 27, 1938, in Augusta, Maine, died July 23, 2002, in downtown New York City) was an American composer, songwriter, author, and actor. He is probably best known for composing You're a Good Man, Charlie Brown, a musical adaptation of the Charles M. Schulz comic strip Peanuts.

None of his other musicals (most notably The Utter Glory of Morrissey Hall in 1979) had been able to match the success of ...Charlie Brown, though he had small success in regional productions (mostly Animal Fair in 1990).

Gesner's song "Happiness" became a hit standard in the 1960s, being recorded by various artists. The latter was also recorded in a smooth jazz version by David Benoit in May 2000, shortly after Charles M. Schulz's death, on an album entitled Here's To You, Charlie Brown: 50 Great Years! The album made it to #2 on the Top Jazz Albums chart.