He is the patriarch of the Boom Boom Family and father of L. A. and Andre. Benjamin Boom Boom is one of the racers of the Steel Ball Run and attacks Johnny Joestar and Gyro Zeppeli to eliminate competitors.
After his son Andre tricks Gyro Zeppeli and Johnny Joestar and manages to transform the first into a human magnet, Benjamin and L.A. attack them unsuccessfully. Benjamin however, manages to exploit Andre's power in a diabolic way: by shooting at him, he manages to drop some of his son's blood on Johnny, therefore turning him into a magnet as well.
By assuming Johnny's identity, he manages to magnetize Mountain Tim too: his plan is to make the three of them approach and be killed by the magnetic power of the Boom Boom family.
However his plan seems to fail, when Mountain Tim uses his Stand to get out of the sticky situation. Forced to close combat, he orders L.A. to cut Oh! Lonesome Me, but because of his son's lack of intelligence, Benjamin is forced to protect him with his Stand.
The rope finally cut, Benjamin's plan seems to work, but he is caught by surprise and killed by Johnny's new power.
Benjamin appears like a big middle-aged man in his late forties. His most peculiar feature is the iron respirator-like mask he constantly wears: when the situation requires, he can fuse it with his own body through is Stand.
He is very aggressive, constantly shouting at his sons (especially L.A.) and badmouthing his wife. He does however care for his family, being more than willing to protect his sons using his Stand as a shield. He seems to hate the mother of his children, who supposedly abandoned the family to "be a whore".
- Main article: Tomb of the Boom 1
Tomb of the Boom 1 grants every member the ability to manipulate iron, though every member develops this ability in a different way. In Benjamin's case, by fusing pieces of metal with his body, the Stand can alter its user's appearance, transforming him into a perfect copy of his target.
This also gives him the ability to create sharp metal blades from his body. The Stand seems to have good defense, being able to deflect bullets without a scratch, and can shrink iron items by removing their iron particles