I read the story in the '50s.
The story was probably in a DC comic.
A college professor uses hypnosis to discover people's past lives (like Bridey Murphy). He discovers that one of his subjects is an alien android who lived as many historic leaders. His last life before the present was Adolph Hitler. His current life is as a custodian at the college.
I misled Trish by failing to say: this was not a superhero comic. It was a 'one and done' story in a science fiction/fantasy/adventure anthology.
I'd like to identify the story so that I can find more of the author's work.