'Arrow' and 'Hobbit' Star Manu Bennett -- Busted for Drunken Knockout at Comic-Con After-Party

One of the 'Hobbit' villains got drunk, and knocked a guy out cold during a Comic-Con after-party, and ended the night in handcuffs ... according to cops and witnesses.

According to police docs, obtained by TMZ, Manu Bennett was hanging with a bunch of people in a San Antonio hotel room ... drinking and having a good time ... until he was asked to leave. Witnesses told police that Bennett -- who played Azog in the 'Hobbit' -- had too much to drink.

Before Bennett left the room he stared down the other guests, and when one of them dared to ask, "What?" ... witnesses say the actor unloaded a knockout punch to the guy's face.

The victim's nose was broken and bleeding. Cops showed up and went to Bennett's hotel room. At first he didn't remember the fight, but then claimed he was defending himself.

Bennett -- who also stars in "Arrow" and the "Spartacus" TV series -- was arrested and booked for assault.