The King

King Standish, who first appeared in Flash Comics # 3 and ran until 41, usually depicted on the few covers he was on as a man wearing a tuxedo, top hat and a domino mask. The King was a wealthy master of disguise so good that he could pretend to be someone else so well that not even people who had known that person for years could detect he was not the genuine article,

As such The King spent most of his adventures taking on the appearance someone else, his only motivation seemed to be for the fun of it. 

Thought by the law to be a criminal, the King was really working in the underworld to bring it down.

His main adversary was a woman known as The Witch who was as good at disguise as he was, only she actually was up to no good. Eventually the two developed feelings for each other, though never seeing the true face of the other.