If Mayhem means Matanza Cueto from Lucha Underground. He was played by Jeff Cobb and Matte took him at 394. If you mean somebody else, specify, because I don't know who else you would mean.
It's not perfect for the concept, but it's close enough to Athens and the birth of the Olympics and makes more sense as a fighting venue. Home of the upcoming NXT Global Series... 479. Roman Colosseum
And I still need a GM and it's impossible to get the perfect person to run this (HHH) so I'll grab someone he works with from time to time and the booker of the best run in ROH history.