UFC middleweight Josh Samman -- who appeared on "The Ultimate Fighter" -- has died after spending several days in a coma ... this according to his "Ultimate Fighter" castmate Gilbert Jamal Smith.
Samman was found unresponsive early Friday morning at an apartment in South Florida. His roommate, Troy Kirkingburg -- a UFC announcer -- was pronounced dead the scene.
It's unclear how the two men died.
There were rumblings that heroin played a role -- but Samman's mother came out and said doctors found no traces of the drug in his system. There were also no signs of foul play according to reports.