Washington Wizards center Jason Collins who's been playing in the NBA since 2001 has revealed he's gay ... making him the first major active American male pro athlete to come out of the closet .
Collins revealed the news in an article for Sports Illustrated ... saying, "I'm a 34-year-old NBA center. I'm black. And I'm gay."
He continued, "I didn't set out to be the first openly gay athlete playing in a major American team sport. But since I am, I'm happy to start the conversation."
Collins and his twin brother Jarron have been high profile athletes since high school ... when they were two of the highest rated prep players in the country.
They both went on to become standouts at Stanford ... and were each drafted into the NBA in 2001.
Jason says he didn't come out to his twin until last summer.
"I'm glad I can stop hiding and refocus on my 13th NBA season."