David Cook (Northern Ireland politician)
David Sommerville Cook (born 1943/1944) is a former politician in Northern Ireland.

Cook works as a solicitor, eventually becoming a senior partner at Sheldon and Stewart Solicitors.

In 1970, Cook was a founder member of the Alliance Party of Northern Ireland (APNI), while he was elected to the party's Central Executive in 1971.

He was elected to Belfast City Council in 1973, a position he held until 1985. In 1978, he became the first non-Unionist Lord Mayor of Belfast since William James Pirrie, a Home Rule Liberal, in 1896–1898.

He stood for APNI in Belfast South in the February 1974 general election, taking just under 10% of the vote.  He was able to improve to 27% of the vote at the 1982 Belfast South by-election.  Following this, he won a seat on the Northern Ireland Assembly representing Belfast South.

In the 1983 general election, 1986 by-election and 1987 general election, he consistently won over 20% of the votes cast in Belfast South. He also stood for Alliance in the 1984 European Parliament election, but took only 4% of the vote. From 1980–84, Cook served as the Deputy Leader of APNI.

In 1994, Cook became the Chairman of the Police Authority of Northern Ireland, but he was sacked from this role in 1996 after losing a vote of confidence. After a critical account of his role appeared in 1998, he undertook a lengthy libel case, ultimately settled out of court. He subsequently sat on the Craigavon Health and Social Services Trust.