I think Muhammad Ali is a good one along with Hank Aaron.
In entertainment I think Sidney Poitier and Sammy Davis Jr. and Justice Thurgood Marshall. The very first political figure to get mainstream notice was Frederick Douglas.
Alexandre Dumas
Betcha you didn't know that French author was black. He wrote "The Three Musketeers" and "The Count of Monte Cristo" and "The Man in the Iron Mask."
Nat King Cole had a national television variety show in 1956, around the same time as Jackie Robinson was playing basball.
In what realm? Although there's never been a period without racism (and it's unlikely there ever will be completely a time without it), there have also been black persons throughout history who were the exception to the "white man" rule, and made a name for himself (or herself) based on their work/worth/personality, and not their color. At the same time, all the people already mentioned were only accepted by some of the people, not all of them.
The question needs to be more specific.