Herbert John Harvey Parker (15 July 1906 – 24 November 1987), normally known as John Parker, was a British politician. He remains the longest-serving Labour Party Member of Parliament (MP), retaining a seat in the House of Commons for 48 years.
He was first elected to represent Romford in November 1935. After boundary changes, he continued as MP for Dagenham from 1945, remaining in the House of Commons until he retired in June 1983. As the longest-serving MP, he was the Father of the House of Commons from 1979 to 1983. When he left parliament in 1983, he was the last serving Member of Parliament to have served in the Commons before or during the Second World War.
Parker was raised in Liverpool. He was educated at Marlborough College and St John's College, Oxford, where he was Chair of the Oxford University Labour Club.
He married Zena Mimardiere in 1943. They had one son.
He contested the seat of Holland with Boston in Lincolnshire in the 1931 general election, but the sitting National Liberal MP James Blindell was reelected.
In the 1935 general election, Parker was elected as MP for Romford in Essex, which he represented until 1945. He was elected as MP for Dagenham at the 1945 general election, a new seat carved out of the Romford constituency. (His Labour colleague Thomas Macpherson was elected in Romford in 1945, but lost the seat to the Conservative John Lockwood in 1950).