Denis Haughey (born 3 October 1944) is a former Irish nationalist politician in Northern Ireland.

Born in Coalisland, Haughey studied politics at Queens University, Belfast,^[1] becoming involved in the civil rights movement and the first Chair of the Tyrone Civil Rights Association^[2] and a founder member of the Social Democratic and Labour Party (SDLP), before becoming a teacher.^[1] From 1972 until 1977, he was the party's Chairman.^[2]

Haughey stood against Frank McManus for the Westminster seat of Fermanagh and South Tyrone in February 1974, splitting the nationalist vote and letting in Harry West of the Ulster Unionist Party.^[3] He unsuccessfully contested North Antrim in the 1975 election to the Northern Ireland Constitutional Convention^[4]

In 1980, Haughey left teaching to work as the full-time assistant to SDLP leader John Hume.^[1] During this period, he served as the party's International Secretary, and represented the SDLP on the Executives of the Party of European Socialists and the Socialist International. At the 1982 Northern Ireland Assembly election, Haughey was elected to represent Mid Ulster, but with other SDLP candidates did not take his seat, and instead joined the New Ireland Forum. He stood unsuccessfully for the Westminster seat of Mid Ulster at every general election from 1983 until 1997.^[2]

In 1989, Haughey was elected to Cookstown District Council, later becoming the leader of the SDLP group on the council. He led the SDLP team in the Brooke-Mayhew Talks and later the talks which led to the Good Friday Agreement. In 1996 he was an unsuccessful candidate in the Northern Ireland Forum election in Mid-Ulster.^[5] At the 1998 Assembly election, he was again elected for Mid Ulster.^[1] However, he lost his seat at the 2003 election,^[2] and in 2004 was unsuccessful in becoming the party's candidate for the European election.^[6]