Sullivan was born in Greene County, Virginia, on February 7, 1912. He started working as a ranger in Shenandoah National Park in 1936. Sullivan was described as a brawny man with a broad, rugged face, who resembled the actor Gene Hackman. He was avoided by people later in life because of their fear of being hit by lightning, and this saddened him. He once recalled "For instance, I was walking with the Chief Ranger one day when lightning struck way off (in the distance). The Chief said, 'I'll see you later.'"On the morning of September 28, 1983, Sullivan died at the age of 71 under mysterious circumstances from a gunshot wound to the head. Officially, he shot himself over an unrequited love lying in bed next to his wife who was 30 years younger and allegedly did not notice his death for several hours. Two of his ranger hats are on display at two Guinness World Exhibit Halls in New York City and South Carolina.