Veteran stand-up comedian and actor Kevin Meaney died Friday ... but it's unclear why.
Meaney was in stand-up comedy for nearly 30 years. His first HBO special hit in 1986, and he made a bunch of appearances on "The Tonight Show" with Johnny Carson. Meaney also had roles in the Tom Hanks movie, "Big," and the 1990 sitcom "Uncle Buck."
The cause of death is unknown so far ... an autopsy is pending.