Robert O. Muller (born 1946) is an American peace advocate. He was born on Long Island, and grew up in Great Neck, New York. He enlisted in the U.S. Marine Corps in 1967, during the Vietnam War. His commission with the Marines began the same day he received his bachelor's degree in business administration from Hofstra University in 1968, and by September of that year he was a combat lieutenant leading a marine infantry platoon. In April 1969, while leading an assault in Vietnam, a bullet entered his chest and severed his spinal cord, leaving him paralyzed from the chest down.