The mother of former WWE superstar Doink the Clown is suing the WWE -- claiming her son suffered serious brain injuries in the ring that led to his death ... and the WWE ignored the problem.
Doink -- real name Matthew Osborne -- died from a drug overdose in 2013 ... but in her lawsuit, Doink's mother says his drug addiction was a result of years of concussions he sustained while wrestling.
Doink's mother says the WWE knew about the dangers of the brain injuries that has plagued WWE wrestlers for years ... and says the organization could have helped her son seek proper treatment.
Doink's mom says the WWE did create a program in 2006 called the "Wellness Program" -- but says it only deceived her son by creating a false sense of security that led him to NOT get adequate treatment for his problems.
But the most dramatic part of her suit ... Doink's mom says Vince McMahon has essentially turned a blind eye to the scores of WWE superstars who have died young over the years -- ignoring huge warning signs that could've saved her son and others.
She lists dozens of examples ... including the Ultimate Warrior, Mr. Perfect, Crush, Bam Bam Bigelow, Eddie Guerrero, Randy Savage, Big Boss Man, Yokozuna, Chris Benoit and more.
Doink's mom is suing for wrongful death, fraud and negligence.
A lawyer for the WWE told the Dallas Morning News ... the suit has no merit and accuses Doink's family of simply trying to get "NFL money."