Gerard Steenson (c. 1957 – 14 March 1987) was an Irish republican paramilitary combatant in Northern Ireland.
A Catholic, he was raised in heavily republican West Belfast. Nicknamed "Doctor Death" by the media and by the Royal Ulster Constabulary for the multiple assassinations he purportedly accomplished, Steenson was widely associated with internecine violence between Irish republican groups. He joined the Official IRA's C Company in 1972 at the age of 14. Two years later, he left to join the INLA upon that paramilitary group's formation, consequent to their split from the Official IRA.
Steenson first came to notoriety in 1975 for killing Billy McMillen, the Official IRA's Belfast leader, during the feud between the INLA and the Official IRA.
In 1986, Steenson, Jimmy Brown and others formed the Irish People's Liberation Organisation (IPLO) with the express intention of wiping out the INLA and IRSP which they viewed as becoming "corrupt" and an obstacle to "the fight for socialism" and "Irish freedom". He argued in letters, written while he was in prison in the early 1980s, that the INLA had become militarily "inefficient" and "undisciplined", which had led, as he wrote, to its involvement in criminality and sectarian attacks.
In 1987, Steenson and fellow IPLO volunteer Tony McCarthy were ambushed and killed, presumably by an INLA active unit, while travelling in a car along Springhill Avenue, in Ballymurphy, Belfast, the site of the killing in 1971 of eleven Catholic civilians by the British Army's Parachute Regiment. Two revenge killings of INLA members followed before the end of the feud.