Chameleon (comics)
The Chameleon was born a Soviet citizen named Dmitri Smerdyakov (Дмитрий Смердяков). In his youth, he was a servant and half-brother to Sergei Kravinoff and eventually became a minor associate to Gustav Fiers. Although Dmitri and Sergei were friends, Sergei was often abusive to Smerdyakov, leading to a combination of admiration and resentment towards Kravinoff. Eventually, Smerdyakov emigrated to the United States of America. As he had made a talent for himself during his youth, impressing his brother by impersonating friends and neighbors, he assumed an even more impressive disguise: the identity of Chameleon. During his first known criminal outing, he impersonated Spider-Man, though he was exposed and arrested. Shortly afterward, Kraven the Hunter himself came to America, and the Chameleon set his old associate's sights on Spider-Man. Both men became long-time enemies of Spider-Man, part of his primary rogues' gallery.
Alpha Centurion
During the "Zero Hour" storyline, Superman was transported to an alternate timeline where he stumbled upon a Metropolis whose hero was the Alpha Centurion, a man named Marcus Aelius from Ancient Rome who had been trained by an alien race called the Virimiru only to return centuries later. Initially joining the gathered heroes, the Alpha Centurion went on to join Extant and Parallax in fighting against the heroes of the DC Universe, siding with Parallax as he promised to restore Alpha Centurion's apparently lost timeline. After the heroes had to restart existence with a new Big Bang, all alternate realities ceased to exist and this Alpha Centurion was no more.