John Gregg (1957 – 1 February 2003) was a senior member of the UDA/UFF loyalist paramilitary organisation in Northern Ireland. In 1984, Gregg seriously wounded Sinn Féin president Gerry Adams in an assassination attempt. From the 1990s until he was shot dead in 2003 by rival associates, Gregg served as brigadier of the UDA's South East Antrim Brigade. Widely known as a man with a fearsome reputation, Gregg was considered a "hawk" in some loyalist circles.