Richard Feynman (1918-1988) was an American physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics (he proposed the parton model).

For his contributions to the development of quantum electrodynamics, Feynman, jointly with Julian Schwinger and Sin-Itiro Tomonaga, received the Nobel Prize in Physics in 1965. He developed a widely used pictorial representation scheme for the mathematical expressions governing the behavior of subatomic particles, which later became known as Feynman diagrams. During his lifetime, Feynman became one of the best-known scientists in the world.

He assisted in the development of the atomic bomb and was a member of the panel that investigated the Space Shuttle Challenger disaster. In addition to his work in theoretical physics, Feynman has been credited with pioneering the field of quantum computing, and introducing the concept of nanotechnology (creation of devices at the molecular scale). He held the Richard Chace Tolman professorship in theoretical physics at the California Institute of Technology.

Feynman was a keen popularizer of physics through both books and lectures, notably a 1959 talk on top-down nanotechnology called "There's Plenty of Room at the Bottom" and "The Feynman Lectures on Physics". Feynman also became known through his semi-autobiographical books ("Surely You're Joking, Mr. Feynman!" and "What Do You Care What Other People Think?") and books written about him, such as "Tuva or Bust!"

He was regarded as an eccentric and free spirit. He was a prankster, juggler, safecracker, proud amateur painter, and bongo player. He liked to pursue a variety of seemingly unrelated interests, such as art, percussion, Maya hieroglyphs, and lock picking.

Feynman also had a deep interest in biology, and was a friend of the geneticist and microbiologist Esther Lederberg, who developed replica plating and discovered bacteriophage lambda. They had several mutual physicist friends who, after beginning their careers in nuclear research, moved for moral reasons into genetics, among them Leó Szilárd, Guido Pontecorvo, and Aaron Novick.