Robert John Jackson (27 September 1948  – 30 May 1998), also known as The Jackal, was a Northern Irish loyalist paramilitary and part-time soldier. He was a senior officer in the Ulster Volunteer Force (UVF) during The Troubles in Northern Ireland. Jackson commanded the UVF's Mid-Ulster Brigade from 1975 to the early 1990s, when Billy Wright took over as leader.

From his home in the small village of Donaghcloney, County Down, a few miles south-east of Lurgan, Jackson is alleged to have organised and committed a series of killings, mainly against Catholic civilians, although he was never convicted in connection with any killing and never served any lengthy prison terms. At least 50 killings in Northern Ireland have been attributed to him, according to Stephen Howe (in the New Statesman magazine) and David McKittrick (in his book Lost Lives).

An article by Paul Foot in Private Eye suggested that Jackson led one of the teams that bombed Dublin on 17 May 1974, killing 26 people, including two infants. Royal Ulster Constabulary Special Patrol Group (SPG) officer John Weir (who was also involved in loyalist killings), also maintained this in an affidavit. The information from Weir's affidavit was published in 2003 in the Barron Report, the findings of an official investigation into the Dublin bombings commissioned by Irish Supreme Court Justice Henry Barron. Journalist Kevin Dowling in the Irish Independent alleged that Jackson had headed the gang that perpetrated the Miami Showband killings, which left three members of the cabaret band dead and two wounded. Journalist Joe Tiernan and the Pat Finucane Centre also made this allegation and adverted to Jackson's involvement in the Dublin bombings. When questioned about the latter, Jackson denied involvement. Findings noted in a report by the Historical Enquiries Team (HET) (released in December 2011) confirmed that Jackson was linked to the Miami Showband attack through his fingerprints, which had been found on the silencer specifically made for the Luger pistol used in the shootings.

Jackson was at one-time a member of the Ulster Defence Regiment (UDR) but was discharged from the regiment for undisclosed reasons. It was stated by Weir, as well as by others including former British Army psychological warfare operative Major Colin Wallace, that Jackson was an RUC Special Branch agent.

Jackson was born into a Church of Ireland family in the small, mainly Protestant hamlet of Donaghmore, County Down, Northern Ireland on 27 September 1948, one of seven children of John Jackson, a farmhand and Eileen Muriel. Some time later, he went to live in the Mourneview Estate in Lurgan, County Armagh before making his permanent home in the village of Donaghcloney, County Down, 5 miles (8.0 km) southeast of Lurgan. In the late 1960s he married Eileen Maxwell, by whom he had a son and two daughters. When the marriage later failed he began a serious relationship with another woman. Jackson made a living by working in a shoe factory and delivering chickens for the Moy Park food processing company throughout most of the 1970s.

The conflict that was known as "the Troubles" erupted in Northern Ireland in the late 1960s, and people from both sides of the religious/political divide were soon caught up in the maelstrom of violence that ensued. Described as a "hard man" in his teens, Jackson took part in the Paisleyite demonstrations against the Northern Ireland Civil Rights Association. In 1972 he joined the locally recruited Ulster Defence Regiment (UDR), an infantry regiment of the British Army, in Lurgan. He was attached to 11th Battalion UDR. On 23 October 1972, a large cache of guns and ammunition were stolen during an armed raid by the illegal Ulster loyalist paramilitary organisation, the Ulster Volunteer Force (UVF), on King's Park camp, a UDR/Territorial Army depot. It is alleged by the Pat Finucane Centre, a Derry-based civil rights group, that Jackson took part in the raid while a serving member of the UDR. Journalist Scott Jamison also echoed this allegation in an article in the North Belfast News, as did David McKittrick in his book Lost Lives.

Around the same time Jackson was expelled from the regiment for undisclosed reasons, he joined the UVF Mid-Ulster Brigade's Lurgan unit. The UVF drew its greatest strength as well as the organisation's most ruthless members from its Mid-Ulster Brigade, according to journalist Brendan O'Brien. The Pat Finucane Centre's allegation that he had taken part in the UVF's 23 October 1972 raid on the UDR/TA depot indicates that he was most likely already an active UVF member prior to being dismissed from the UDR. Anne Cadwallader states in her 2013 book Lethal Allies that Jackson was expelled from the UDR on 4 March 1974; by then he was discernibly involved in UVF activity. As the Provisional IRA continued to wage its militant campaign across Northern Ireland throughout 1972, many loyalists felt their community was under attack and their status was being threatened and sought to retaliate against Irish nationalists and republicans by joining one of the two main loyalist paramilitary organisations, the illegal UVF or the legal Ulster Defence Association (UDA). The proscription against the UVF was lifted by Merlyn Rees, Secretary of State for Northern Ireland, on 4 April 1974. It remained a legal organisation until 3 October 1975, when it was once again banned by the British government.

Many members of loyalist paramilitary groups such as the UVF and UDA managed to join the UDR despite the vetting process. Their purpose in doing so was to obtain weapons, training and intelligence. Vetting procedures were carried out jointly by the Intelligence Corps and the RUC Special Branch and if no intelligence was found to suggest unsuitability, individuals were passed for recruitment and would remain as soldiers until the commanding officer was provided with intelligence enabling him to remove soldiers with paramilitary links or sympathies.