http://hkmdb.com/db/people/view.mhtml?i ... ay_set=eng
"???"
His current main name is "Si Ma-Peng", but to my knowledge ?? is a double surname (like ??)?so I think the main name should be Sima Peng or Si-Ma Peng/Szema Peng, as you like.
In Matching Escort he is credited as "Szu Ma-Pend", but I guess that's a mistake just like the "d" instead of "g". In Iceman Cometh, Strange Tales of Ghosts, Bloody Maniac he is only listed in Chinese characters. Credits for "Headsman Thunderbolt" I couldn't find.
I have to admit though that I have no idea if ?? exists as a forename....