Richard Feynman famously played the bongos. His enthusiasm for percussion became one of the most recognizable parts of his public image, alongside his work as a Nobel Prize-winning physicist.
Feynman began playing drums during the Manhattan Project years at Los Alamos, where colleagues remembered him performing on drums and using music as a break from wartime research. During a later stay in Brazil, he became fascinated by samba and learned to play the frigideira, a metal percussion instrument made from a frying pan. He also played bongo and conga drums.
At Caltech, Feynman played bongos with friends and sometimes performed in musical productions. Ralph Leighton, his friend and later collaborator, was among the people who played with him. Photographs and stories of Feynman drumming helped create the enduring image of the physicist as an unconventional, playful character.
“Drums” is a defensible broad description, but “bongos” is the canonical answer expected by this question. Piano and guitar are not the instruments most famously associated with him.