The Quarrymen were an anti-gargoyle organization founded by John Castaway (a.k.a. Jon Canmore). The Quarrymen, wearing masks to conceal their identities and wielding special energy-hammer weapons, initiated various attacks on the gargoyles.
Their first such action was an attack on Goliath and Elisa Maza when they went out on a sort-of date. The pair were saved thanks to Vinnie, who was disillusioned by the Quarrymen's brutal methods and subsequently took a job in Japan.
Greg Weisman's Master Plan
The Quarrymen would be a continuing threat to the Manhattan Clan and, over time, gargoyles everywhere. It would have been revealed that they were being funded by the Illuminati Society, and while they'd have become unpopular over time, in 2198 they would have again gained strength playing upon humans' fear of what's different when the Space-Spawn invaded.
The Goliath Chronicles
The actions of the Quarrymen escalated, including attacks on the pro-gargoyle PIT Crew and using military-grade artillery against the Manhattan Clan (which got Castaway and some of his cohorts arrested). The Quarrymen were crippled, if not destroyed, when John Castaway led an attack on a train that was transporting Bronx and Angela to a location to await trial. This act endangered many innocent people on the train, and Castaway and company were discredited totally when the gargoyles saved the train passengers. The Quarrymen present were arrested, and the gargoyles finally received some acceptance.