His sister, Kayley Gable, also posted an emotional tribute to the aspiring actor and host of the reality TV show "Cheaters."
“My brother was found unresponsive this morning by his fiancé (sic) and didn’t wake up .. I LOVE YOU CLARKIE I’m so sorry we couldn’t save you my heart is broken and shattered RIP,” Gable wrote on Facebook.
Clark Gable III was filming the crime drama "Sunset at Dawn" and had recently finished another film called "Heckle" at the time of his death, Variety reported.
A cause of death has not been released.
His famous grandfather was a major Hollywood movie star during the 1930s and 1940s, known as the King of Hollywood, and is probably best remembered for his role as Rhett Butler in "Gone with the Wind," but he made dozens of memorable classic films, including "Mutiny on the Bounty," "Test Pilot," "Boomtown," and "It Happened One Night," to name just a few. He died in 1960 from a heart attack shortly after he wrapped filming on "The Misfits," co-starring Marilyn Monroe. The American Film Institute named Gable the seventh-greatest male star of all time.