Lawrence David O'Brien (March 31, 1951 – December 16, 2004) was a Canadian politician. O’Brien represented Labrador in the House of Commons of Canada as a Liberal from 1996 until his death in 2004.

Born in L'Anse-au-Loup, Newfoundland and Labrador, O’Brien was an adult education instructor, a public servant, a teacher, and from 1985 to 1996, and a town councillor in Happy Valley-Goose Bay, Newfoundland and Labrador. He served as Parliamentary Secretary to the Minister of Fisheries and Oceans from 1999 to 2001. He was a strong supporter of a 2003 constitutional amendment which officially changed the name of the province of Newfoundland to "Newfoundland and Labrador".

O'Brien was a candidate for the provincial Liberal nomination in the district of Cartwright-L'anse au Clair in 1996. After his loss in that race, he entered, and won, the federal Liberal nomination for the by-election in the riding of Labrador, vacated by the appointment of Bill Rompkey to the Senate. O'Brien was elected in the federal by-election on March 25, 1996,^[1][2] and re-elected in the general elections of 1997,^[3] 2000,^[4] and 2004.^[5]

He was diagnosed with cancer in 1998^[6] and died on December 16, 2004, in St. John's, Newfoundland and Labrador.^[7] On January 31, 2005, the members of the House of Commons paid respects to him and his career.