The Ravens fan who was caught on video brutally attacking two Washington Commanders supporters has turned himself in to Baltimore cops ... after a warrant was issued for his arrest.
24-year-old John Callis, wearing a button-up shirt, turned himself in to police Monday morning ... where he was seen being led away in handcuffs.
FYI, last week cops told us Callis was wanted for first-degree aggravated assault and three counts of second-degree assault.
Of course, video of the attack went viral ... showing what police say is Callis -- wearing a Lamar Jackson jersey -- attacking two unsuspecting Commanders fans after the Ravens defeated Jayden Daniels' squad on October 13.
He knocked one fan out cold and pushed another into a brick wall. The second man seemingly escaped without taking further damage.
In the immediate aftermath, Callis showed no remorse for his actions ... flexing right at the camera and saying, "I don't lose!"
Well, consider this a massive L ... first-degree assault in Maryland carries a potential penalty of 25 years in prison.