You gotta see this! Undefeated heavyweight champion boxer Deontay Wilder BEAT THE HELL out of a real life Internet troll who had been harassing him for years ... and TMZ Sports has the insane video.

The guy who got his face bashed in is Charlie Zelenoff -- a wannabe fighter who's been trolling Wilder for years with harassing phone calls and deeply personal jabs on social media.

Wilder claims Charlie has not only hurled racial slurs at him -- but also made disparaging comments about his young daughter, who was diagnosed with spina bifida.

Zelenoff had recently challenged Wilder to fight him at a boxing gym in L.A. -- and Wilder, deciding enough was enough, met him at the Hollywood Boxing Gym late Wednesday night.

Wilder tried to fight Zelenoff in the ring -- but CZ threw a c heap shot and ran for the door (see video below embedded to the left).

When he finally returned, the squared off on the main floor of the gym -- and what ensued was a pure ass kicking.

When Zelenoff picked himself up off the floor ... a furious Wilder told him, "Don't you ever call me a n**ger again. Don't you ever say you're going to tape my daughter."

Zelenoff eventually ran from the building ... again ... but not before saying, "I'm the best. I'm still the best."

*This article provided to Doghouse Boxing from our friends at http://www.tmzsports.com/

Also recent from by TMZ:
Pacquiao bumps into Justin Bieber while dropping $20k
Chris Brown Trained to Fight w/ Boxing Champ Andre Berto
Kassim Ouma Jailed - K.O.'s Guy Over Alleged Gay Passes
Dewey Bozella - 'Hurricane' Carter Inspired Me
George Foreman - Bernard Hopkins Should Retire
Mayweather & Miss Jackson - We've Broken Up FOR GOOD!
Danny Garcia - 1st Thing I Do After a Fight... HAVE SEX!
'Black Dynamite' Star - I'd Beat Floyd Mayweather In an MMA
Andre Berto - TMZ Exclusive - "It's brutal man, it's brutal"
Floyd Jr. - New Million Dollar Watch...
Floyd Mayweather uses Justin Bieber Music to inspire
Floyd Mayweather Jr. Accusers - Injury Photos
Floyd Jr Allegedly Involved in Kidnapping & Brutal Beating
Mike Tyson has Priceless Financial Advice for Antonio Tarver
Antonio Tarver Arrest Details & Mug Shot - TMZ Exclusive
Pernell Whitaker's Mom: I Can't Believe He EVICTED Me!
Floyd Mayweather Sr vs. Roberto Guerrero - TMZ Exclusive
Roy Jones Jr. - I'm Running for Mayor! - TMZ Exclusive
Pacquiao: Yes, I Eat Aborted Duck Fetuses / Cooked Alive
Kelly Pavlik HOSPITALIZED... After Collapsing at Court
Kelly Pavlik Arrested! Cabbie: 'That Drunk F*** Ripped Me Off!'

Tune in to TMZ on TV weekdays Monday through Friday (check http://www.tmz.com/when-its-on for syndicated/local listings at the bottom of the page)

Visit the TMZ Store: http://tmzstore.com

Tune in to TMZ on TV weekdays Monday through Friday (check http://www.tmz.com/tmztv/ for syndicated/local listings).

This article provided to Doghouse Boxing by our good friends at TMZ.com.

For much more Boxing news updates, visit the home page HERE at Doghouse Boxing. Also make sure to follow Doghouse Boxing's news wire