Clark Gable -- Stabbed in the Chest

Clark Gable III -- the grandson of Hollywood's most famous actor ever -- was stabbed in the rib cage at a house party near Los Angeles.

It all went down in Calabasas last month -- we're told CG3 got into it with some guests after he allegedly called somebody a very bad name. A fight broke out and someone plunged a knife into Gable -- who looks remarkably like his granddad.

We're told Gable suffered lung damage and spent a week in the hospital. Judging by the "thumbs up" from the picture, he's doing just fine.

One person has been arrested and authorities are looking for another suspect.