Stephen Koepfer, aka Sambosteve, is a master of sport in Sambo, a grappling coach, stuntman, filmmaker and lifelong martial artist from Queens, NY. He was a technical adviser for History Channel's "The Human Weapon," and has been a stunt performer in "John Wick Chapters 2 & 3," "The Blacklist," "The Punisher," "Ray Donovan" and many other productions.