He had three children from his first marriage: Deborah, Alan and David.

According to the book "Weird NJ" (Sceurman, Mark and Mark Moran, Barnes and Noble Books, 2004 ISBN 0-7607-3979-X) he was a descendant of the Morris County Van Cleefs who were infamous in the area for their strange living and "procreational" efforts. In fact, one trait that Lee had was that he had one green eye and one blue eye. According to the book, "this telltale characteristic was corrected in the movies with colored contact lenses".

Son of Clarence Leroy Van Cleef and wife Maria Lavinia Van Fleet, both mostly of Dutch ancestry.

He had almost given up his acting career in the mid-'60s and turned to painting when he was cast by Sergio Leone in Per qualche dollaro in pił (1965). It made him a superstar in Europe and restarted his career in the US, making him again a recognizable and bankable name.

Was the inspiration for the character Revolver Ocelot in the "Metal Gear" series of games.

One episode of his short-lived TV series, "The Master" (1984), was titled "The Good, The Bad and the Priceless".

He was missing the last joint of his middle finger, a disfigurement prominently featured in the climactic gunfight of Buono, il brutto, il cattivo, Il (1966). He actually lost it while building a playhouse for his daughter, although there were rumors that it happened in a road accident or a bar fight.

During one summer in the early 1950s he was a camp counselor in NYC for Marc Furstenberg.

Was portrayed as a bounty hunter in the Lucky Luke comic book "The Bounty Hunter".

Interviewed in "Bad at the Bijou" by William R. Horner (McFarland, 1982).