John Weir (loyalist)

John Oliver Weir (born 1950) is an Ulster loyalist born and raised in the Republic of Ireland. He served as an officer in Northern Ireland's Royal Ulster Constabulary's (RUC) Special Patrol Group (SPG) (a tactical reserve unit), and was a volunteer in the illegal Ulster Volunteer Force (UVF). As a member of the UVF's Mid-Ulster Brigade led by Robin "the Jackal" Jackson, Weir was a part of the Glenanne gang, a group of loyalist extremists that carried out sectarian attacks mainly in the County Armagh area in the mid-1970s.

Weir and his RUC colleague Billy McCaughey were convicted of the 1977 sectarian killing of Catholic chemist William Strathearn and sentenced to life imprisonment. Weir's affidavit which implicated Jackson, other members of the Glenanne gang, soldiers of the Ulster Defence Regiment (UDR), and his colleagues in the RUC and SPG, in a series of sectarian attacks, including the Dublin and Monaghan bombings, was published in the 2003 Barron Report, the findings of an official investigation into the 1974 car bombings commissioned by Irish Supreme Court Justice Henry Barron.