His name in the original Japanese version media is Mister Satan. It was changed to Hercule in FUNimation's English dub and Viz Media English version of the manga. In the U.S. edition of Shonen Jump it is explained that Hercule is the real name of the character while Mr. Satan was his stage name though no such explanation was present in the original. He is voiced by Daisuke Gouri in the original Japanese version, Chris Rager in the FUNimation version and by Don Brown in the English version from the UK and Canada. (Source: Wikipedia)