This character showed up in one comic only but the story had an impact on me. Muhammad X is the name of a DC comics superhero operating out of Harlem. His name is a combination his two heroes who should be obvious. He was introduced in a Superman comic as Superman one day found his way to Harlem. Muhammad X, who apparently had density and possibly gravity powers, was angered by Superman's presence saying that Black people need Black role models and shouldn't depend on White heroes that never come to Harlem anyway. Superman was taken aback by this and went to talk to various people in his support group. After talking to Steel's niece he found out there were quite a few other Black superheroes operating that he had not heard of. (I hadn't heard of them either.) When he finally returned to talk with Muhammad X he tried to explain that he was above the color issue. The story ended with Muhammad X saying something like, "Whatever lets you sleep at night."
Obviously the character was created to make a point and rightfully that point wasn't resolved in the comic book. Whether or not the character had a secret identity we may never know. I'm not too fond of the fact that Muhammad X showed up mostly as an angry Black man but I am happy that the subject matter found its way into a mainstream comic. I have to give some credit to the writers Jeph Loeb & Geoff Johns, neither of whom are Black, for writing this story. When I read it I was more than a little suprised and had to show it to someone.