The 1981 by-election held in Fermanagh and South Tyrone on 9 April 1981 is considered by many to be the most significant by-election held in Northern Ireland during the Troubles. It saw the first electoral victory for militant Irish republicanism, which the following year entered electoral politics in full force as Sinn Féin. The successful candidate was the IRA hunger striker Bobby Sands, who died twenty-six days later.
The by-election was caused by the death of the sitting MP, Frank Maguire. When Sands' candidacy was announced the party came under pressure to withdraw in his favour, as putative candidates Bernadette Devlin-McAliskey and Noel Maguire had done, although initially it was said that the mainstream of the party was resistant. On the last day for nominations the party executive decided not to stand, explaining that they wished to concentrate on local government elections which would take place in May; there was speculation that the executive did not share the local party's confidence and feared a poor result. The SDLP decision not to stand in the by-election caused a great deal of dissent within the party.
There were 3,280 spoilt ballot papers.