1. The Crime Syndicate Of Amerika
The Crime Syndicate of Amerika is first alternate version of the Justice League to sprout up following the events of the Crisis on Infinite Earths. That event erased the Multiverse, but left the Antimatter Universe, also known as the Qwardian Universe within DC's continuity.
Within the Antimatter Universe, the Crime Syndicate existed as an evil version of our favorite superheroes only they were far more dastardly than their previous versions.
Superman was called Ultraman and he had no qualms about disintegrating anyone who bothered him. Batman's evil version, Owlman would stop at nothing to kill his enemies, and the Flash's alternate, Johnny Quick, was a drug addict.
The other members of the roster included Superwoman, the evil version of Supergirl, and Power Ring, the evil Green Lantern. The group came into conflict with the JLA when they crossed into each other's universes to restore order/create chaos. The fight between the two groups was brutal and one of the best conflicts in Justice League history.