The Guardian is a superhero legacy that is notorious for its many clones. The Golden Age Guardian was Jim Harper, a police officer in Metropolis' Suicide Slum, friend and ally of the Newsboy Legion. He was a member of the war-time All-Star Squadron. His grand-cousins are Roy Harper, Jamie Harper and "Famous Bobby" Harper.

Years later, Harper was cloned by Project Cadmus, and several other clones were made from the genetic material of either Harper or his clone. Other people who took the alias were Mal Duncan in the Silver Age and Jake Jordan, the Manhattan Guardian.