Shannon Briggs -- Reign Of Klitsch-Terror Continues ... Crashes Champ's News Conference

Shannon Briggs is like Freddy Krueger, Jason Voorhees, and Michael Myers all wrapped up in one ... 'cause no matter what Wladimir Klitschko does ... he just keeps coming for the boxing champ.

FYI -- Briggs has been trying to bait Hayden Panettiere's baby daddy into a fight for MONTHS ... harassing Wlad at restaurants, training sessions, the mall and even crashing a paddleboard ride.

And moments ago, Briggs was at it again ... popping up in NYC to scream at Wlad, who was in the middle of a media event for the big Klitschko vs. Bryant Jennings fight this weekend.

Check out the hilarious video -- Briggs (who's shirtless the entire time) actually gets his chance to plead his case to TMZ Sports saying it's a travesty he's not fighting Wlad in his hometown of NY.