Patrick John Mercer (born 26 June 1956) is an English author and former politician. He was elected as a Conservative in the 2001 general election, until resigning the party's parliamentary whip in May 2013 following questions surrounding paid advocacy, and was an Independent MP representing the constituency of Newark in Parliament until his resignation at the end of April 2014 when a Standards Committee report recommended suspending him for six months for "sustained and pervasive breach of the house's rules". He was Conservative shadow homeland security minister from 2003 to 2007, when David Cameron forced him to resign after he had made remarks about racism which Cameron found unacceptable.

Mercer is a frequent commentator on defence and security issues, having served as a colonel in the British Army and as a BBC journalist. He has to date written four military novels and is a patron of the Victoria Cross Trust.

Born in Stockport in Cheshire in 1956, Mercer is the son of Eric Mercer, who became Bishop of Exeter. His mother was born in Lincolnshire and his father was trained for the priesthood at Kelham Theological College near Newark.

Mercer was educated at The King's School, Chester, and Exeter College, Oxford, where he read history. He was later commissioned after training at the Royal Military Academy Sandhurst. Whilst there, he was one of a number of cadets interviewed for an edition of the BBC's Panorama programme.

Mercer followed his father, who saw wartime service in the Sherwood Foresters (Notts & Derby Regiment), into the British Army. He was commissioned into the Worcestershire and Sherwood Foresters Regiment on 8 March 1975 as a second lieutenant. His service number was 499748. On 8 March 1977, he was promoted to lieutenant. He was promoted to captain on 8 September 1981, and to major on 30 September 1988. On 30 June 1994, he was promoted to lieutenant colonel, then to colonel on 30 June 1998.

During his time in the Army, Mercer completed nine tours in Northern Ireland and latterly commanded his battalion in Bosnia and Herzegovina, Canada and Tidworth. Mercer served at both the Staff College, Camberley, and the Army's University at Cranfield.

Mercer was Mentioned in Despatches in 1983 for "gallant and distinguished service in Northern Ireland during the period 1 November 1982 to 31 January 1983". He earned a gallantry commendation in 1990. He was made an MBE on 12 October 1993 "in recognition of distinguished service in Northern Ireland". He was made an OBE on 13 May 1997 "in recognition of gallant and distinguished services in the former Yugoslavia during the period 21 June to 20 December 1996". He left the Army in 1999 as a colonel, He retired from the army on 1 September 1999, his last posting having been as head of communications and strategy at the Army Training and Recruiting Agency.^{[citation needed]}

After leaving the Army, Mercer was a defence reporter for BBC Radio 4's Today programme. He reported from trouble spots, including Kosovo.