'Tattoos After Dark' Star -- Artist Sued For Molly Wopping Good Samaritan

"Tattoos After Dark" star Asaru Mushavu put his mark on a woman's face -- in the form of a nasty bruise -- after he cold-cocked her for no reason outside of his tattoo parlor ... according to a new lawsuit.

Corey Fortenberry claims Mushavu attacked her last year while she was helping a drunk friend who was puking in front of "House of Ink" -- the Venice tattoo shop featured on the TV show.

According to the police report, Mushavu saw the woman throwing up, came out of the shop and yelled, "What the f*** are you doing? Who the f*** is going to clean that up?" ... and then pushed Fortenberry and punched her in the face.

Fortenberry claims Mushavu left a bruise that's still visible a year later.

A rep for Mushavu tells TMZ ... it's a frivolous lawsuit and he expects it to be dismissed.