John McClain, Michael Jackson Estate Co-Executor, Dead at 71

John McClain, the co-executor of Michael Jackson's estate and a veteran music executive and producer has died ... TMZ has learned.

A rep for McClain tells TMZ ... John died Tuesday. Sources with direct knowledge tell us been had been sick for several years, though it's not yet clear whether that illness contributed to his death. We're told he passed in Malibu.

In addition to his role as co-executor of the MJ estate -- along with John Branca -- McClain produced hits for Michael, Janet Jackson, Ice Cube and Dr. Dre.

He was also an A&R executive at A&M Records who not only oversaw Janet's breakthrough album, "Control," but also urged the label to sign new acts like Mark Wahlberg's Marky Mark & The Funky Bunch.

McClain and Branca were appointed co-executors of the MJ estate in 2009, after Michael's death. They not only got the estate out from under Michael's heavy debt, but turned it into a massively lucrative empire, reportedly worth billions of dollars.

They spearheaded the "Michael" biopic, the Broadway musical, a Cirque du Soleil production and the film, "This Is It" ... about Michael's preparation for his final ill-fated tour.

McClain personally had a hand in the production of Michael's posthumous hits like "Love Never Felt So Good" and "Much Too Soon."

McClain was 71.