William McMullen

William McMullen (1888–1982), sometimes known as Billy McMullen, was an Irish trade unionist and politician.

Born into a Protestant family in Belfast, McMullen began working in the shipyards and became an active trade unionist. He met James Connolly in 1910, and was thereafter Connolly's most prominent supporter in Belfast, acting as the first Chairman of the Irish Labour Party in the city. Becoming a full-time official for the Irish Transport and General Workers Union (ITGWU), McMullen was a strong opponent of the partition of Ireland.

At the Northern Ireland general election, 1925, McMullen stood in Belfast West for the Northern Ireland Labour Party. Despite coming bottom of the poll, he was elected on transfers from Joe Devlin, the only Nationalist Party candidate. In Parliament, he challenged the Ulster Unionist Party over unemployment, and in 1928, he joined the rest of the party in walking out, earning themselves suspensions from the body. For 1927–28, he was the President of the Irish Trades Union Congress.

Following the restructuring of constituencies, McMullen stood in Belfast Falls in 1929. The Nationalist Party stood Richard Byrne, a publican and landlord. Devlin offered to secure McMullen a seat in the Senate of Northern Ireland should he stand down, but McMullen refused the offer. He produced a newspaper, the Northern Worker, claiming that Byrne was a slum landlord. Byrne secured an injunction to stop distribution two days before the election, and beat McMullen by around 1,400 votes.

In 1934, McMullen was a supporter of the Republican Congress movement, a left-wing split from the Irish Republican Army, unsuccessfully contesting Belfast Central in a by-election. He later moved to Dublin to take up a post as the President of the ITGWU. He served three years as a member of the Seanad Éireann. This was interrupted by bankruptcy. In September 1953, he resigned to join the board of Córas Iompair Éireann.