The Juggernaut is the ghost of Horace "Breaker" Mahoney, and the twelfth ghost in the Black Zodiac.
Horace was abandoned by his mother at birth, and thus raised by his father. As a child, Horace grew to such a grotesque height and appearance that he was constantly ostracized.
Mr. Mahoney eventually put Horace to work at his junkyard, crushing up old cars. Eventually, Mr. Mahoney died, and Horace was left alone and finally snapped. He became a serial killer, picking up female hitchhikers to take back to his junkyard, rip to shreds with his bare hands, and feed the remains of to his dogs!
However, Horace's seventh to-be victim turned out to be an undercover police officer, who had a SWAT team surround the junkyard, and arrest Horace.
However, the powerful man was able to break free of his cuffs and kill three police officers before he was brought down in a rain of bullets. They then added one final shot to the head, just to be sure.
Following his death, Horace's earth-bound spirit haunted the junkyard, brutally killing anyone who entered. This caused the junkyard's ghost population to rise to about 40 by 2001.
Cyrus and his team, including Dennis, arrived at the junkyard in 2001 to capture the ghost to become the Juggernaut. They used a tape-recorded Latin chant played across a megaphone to successfully draw the Juggernaut into a containment cube, but not before he savagely and brutally killed Cyrus's entire team, save Dennis.
The Juggernaut was then moved to the basement of the house.
He was the twelfth and final ghost to be released, and once he was, he joined the Hammer in the attack on Dennis. Once the two overpowered Dennis, the Juggernaut brutally finished him off by breaking his back on a pole. Shortly after, the Latin chant caused the Juggernaut, along with the other 11 ghosts, to go to the centre of the machine and power it up.
When the Juggernaut and the other ghosts were freed from Cyrus's trance, they threw Cyrus into a rotating crest of rings.
When the house exploded, destroying its walls, all twelve ghosts escaped the house and into the woods.