Rock Slag and Gravel Slag are two cave people.
They are two bulky cavemen with the same identical size. The only difference is that Rock Slag has dark gray body hair and Gravel Slag has light gold body hair.
Not much is known about their personality, but they are shown to be huge fans of Captain Caveman and are shown to cheer for him in the audience.
The Slag Brothers entered the stadium when Captain Caveman introduces his friends. They were shocked when Blue Falcon insults Cavey when he is called a "little man". They were then laughing at Scooby when he tries to get a hand on his super suit's abilities. They were running away from Dick Dastardly's Rotten Robot army as he kidnaps Scooby.
A image of the Slag Brothers in the Boulder Mobile is on Dastardly's prison wall as Muttley busts him out of jail.
- SCOOB! (no lines)