The mall's most dangerous man.

Ultimate Fighting Championship (UFC) hall-of-famer, Ken Shamrock, was questioned by police at a California mall recently for beating down a would-be attacker who jumped on his back while he was trying to break up a cat fight.

Turns out it was a woman who Shammy mistook for a man.

Shamrock's rep tells TMZ ... he threw the person off of his back and followed up with a move that knocked the attacker to the ground. After the person was incapacitated, the crowd shouted at Ken, "You just hit a girl." Ken took a closer look and realized the attacker was in fact a female .. so he immediately backed off.

But law enforcement sources tell TMZ ... Shamrock probably won't be prosecuted because officials don't feel the woman he knocked to the ground is a "victim." In fact, they believe Ken was acting in self-defense.

Shamrock (28-15) hasn't competed since a technical knockout (TKO) loss to Mike Bourke at the King of the Cage (KOTC) "Platimun" event in late 2010. The mixed martial arts (MMA) pioneer is widely-considered one of the founding fathers of the UFC, but struggled throughout his 40's (going 3-7) in an attempt to stay relevant inside the Octagon.

At least we know he's still good enough to beat the average shopper.