He is the patriarch of the Boomboom Family and father of L.A. and Andre. Benjamin Boomboom is one of the racers of the Steel Ball Run and attacks Johnny Joestar and Gyro Zeppeli to eliminate competitors.
Benjamin appears like a big middle-aged man in his late forties. His most peculiar feature is the metallic apparatus covering the bottom of his face, which he can sink inside his face to change facial features. He wears a dotted cowled, hooded cloak and an iron mask that covers his jaw.
Benjamin is a murderous and greedy man, who targets other competitors in the Steel Ball Run to get ahead and obtain the prize money.
Benjamin is very aggressive, constantly shouting at his sons (especially L.A.) and badmouthing his wife. Although he protects his sons using his Stand as a shield, he pays no mind to the agonizing Andre and leaves him alone. 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 2 3 grants every member of the Boomboom family the ability to manipulate iron in different ways. Benjamin manipulates pieces of iron by putting them under his skin, allowing him to change the appearance and hide weapons.
Steel Ball Run
The Boomboom Family participates in the Steel Ball Run, aiming to be at the first, second and third place to maximize their gains. Lost in the mass of the racers during the first stage, the Boomboom Family assassinates three other competitors named Max Becker, David Hagen and Paul Lukather by using Tomb of the Boom 1 2 3 to magnetize them and make they collide.
During the second stage, the Boomboom Family follows Johnny Joestar and Gyro Zeppeli in the desert because of Oyecomova, who has put a bounty on Gyro. Andre is sent to trick them using the pretense of having been bitten by a poisonous lizard and soon enough Gyro kicks Andre's knife aside, magnetizing his leg. The rest of the family comes.
Gyro's feet is invaded by steel and the duo realises that they are dealing with enemies that are assassinating the competition. They realise that the Boomboom's ability is a magnetic power when Johnny's pistol is disassembled and the pieces are attracted to Gyro's feet. Benjamin Boomboom, the patriarch, destroys an incoming Steel Ball aimed at him with his magnetism. Andre's knife flies towards Gyro's neck but he blocks it. Furious at Gyro for almost letting him die, Andre is the first to charge closer to Gyro. Gyro throws his remaining ball at a rock, making a piece of rock shoot through Andre. Seeing the Boomboom Family circle around them, Gyro understands that the magnetism is tied to his proximity to them and thus, the duo flees. As they move away from the Boomboom, the magnetisms weakens but Benjamin shoots through the hole in Andre, splashing some of Andre's blood on Johnny.
Benjamin, knowing he's followed by the cowboy Mountain Tim, manipulates pieces of metal into his face to make himself look like Johnny. Benjamin fakes surrendering to have Mountain Tim approach and throws his horseshoe at the cowboy, splashing some of his blood on him before crawling inside the briar patches. Mountain Tim reveals his ability Oh! Lonesome Me, allowing the cowboy to disassemble his body along his rope, and tries to grab Benjamin. However, Benjamin cuts the rope with a sharp piece of metal embedded in his face and escapes in the briar patches.
Mountain Tim catches up to Johnny and Gyro. As the family observes the incoming demise of their three enemies, Andre feels unwell because of his wounds and Benjamin leave him behind. However, Mountain Tim uses his power to tie himself to two rocks before he can collide with Johnny and Gyro. L.A. approaches and draws Tomb of the Boom 1 2 3 in the sand to summon it. He activates the iron sand and the sand binds all three horsemen. Mountain Tim shoots at L.A. but Benjamin protects him and Mountain Tim is bound by the sand. Tim collides with Johnny and Gyro but Johnny grabs a bullet, hoping to use the Spin with it. He creates a Spin, but Benjamin stomps his hand to deprive him of this weapon. Thinking himself victorious, Benjamin is taken by surprise when Johnny's nails spin and he shoots them, cutting Benjamin in half.
- “We were looking for mines in the cursed mountain in the desert, which was despised by local Indians... the Indians said bad luck would come to us, but we've only become happy!! We'll eliminate anyone who's in the way! And the Boomboom Family will run as the leader!”
- “Do you feel blessed? We're such a blessed family.”
- “They've uniteeed! I wonder how far their organs will fly out... can we get a new intestine record??”