50 Cent Sued Over Violent Attack

50 Cent employs violent known criminals who viciously attack women when they don't get their way ... this according to a new lawsuit.

According to the suit, obtained by TMZ, 50 Cent hired a guy named Dwayne McKenzie -- although it's not clear exactly what McKenzie did for the rapper.  The suit alleges McKenzie invited some women over to 50's mansion in Connecticut.  During the party, McKenzie began making "graphic and vulgar sexual requests" of one woman.

The plaintiff, Vasti Ortiz, apparently became uncomfortable and started to leave.  She claims that's when McKenzie ordered another woman to start beating on her while he held her down ... badly hurting her.

So why is 50 being sued, aside from the fact that he's rich?  Ortiz claims 50 knew or should have known McKenzie was a known criminal who had assaulted in the past.

50 was not present during the alleged attack.