'Back to the Future' Reunion Was Among Matt Clark's Last Appearances

"Back to the Future" actor Matt Clark has passed away ... but he got to connect with Michael J. Fox for one more time-traveling chat, TMZ has learned.

We broke the news ... Clark, whose illustrious film and TV resume goes back decades, including 'BTTF: Part III,' died in his Texas home on Sunday. He was 89.

A source with knowledge tells TMZ ... Clark was a part of the big “Back to the Future” reunion at the Dallas Fan Expo last year in Texas for the film's 40th anniversary ... and while there, he and MJF chopped it up backstage. Clark was also part of the cast Q&A.

Clark appeared in several Westerns on the big and small screens alongside the likes of Clint Eastwood and John Wayne ... and he appeared in the '80s cult classic "The Adventures of Buckaroo Banzai Across the 8th Dimension."

He also appeared on the sitcom "Grace Under Fire" ... along with classic shows including "Bonanza," "Kung Fu," and "Dynasty." His last role before he died was a prospector in the 2014 film "A Million Ways to Die in the West."

His family told us ... Clark was an "actor's actor" who loved and respected the job but was not concerned with stars and fame. He was impressed when working with good people who loved their families. He felt "lucky" about his career ... and "he died the way he lived, on his terms."

Clark was 89.