Robert Renwick Mortimer (born 23 May 1959) is an English comedian, television presenter, writer and actor. He is one half of the comedy double act Reeves and Mortimer with Vic Reeves, and appears in the Mortimer & Whitehouse: Gone Fishing series with Paul Whitehouse. He has appeared on TV panel shows such as Would I Lie to You? and Taskmaster.

Mortimer was born in Middlesbrough on 23 May 1959, and grew up with three brothers in the town's Linthorpe area. His father died in a car crash when Mortimer was seven. At around the same time, Mortimer accidentally burnt down his family's home with a firework. He attended King's Manor School in Middlesbrough, where his schoolmates included future sports presenter Ali Brownlee. A keen football fan, he had trials for local club Middlesbrough, but abandoned his footballing dreams due to early-onset arthritis.

Mortimer left school with three A-Levels and went on to study law at the University of Sussex and University of Leicester. There, he became a punk, and started a band called Dog Dirt. After leaving university with an LL.M. in Welfare Law, he moved to London and became a solicitor for Southwark Council. He then moved to a private practice in Peckham, where his work with Public Health Act cases regarding cockroach infestations of council properties led to a local paper, the South London Press, dubbing him "The Cockroach King". According to his autobiography, he was mugged during this time by one of his clients, who stopped and apologised after recognising him; he continued to represent the client.

In 1986, Mortimer went to the Goldsmiths Tavern in New Cross, London, to see a new show by the comedian Vic Reeves. Mortimer was impressed by the performance, particularly the character Tappy Lappy, which was Reeves attempting to tap dance while wearing a Bryan Ferry mask and planks on his feet. Mortimer approached Reeves after the show, and the two began writing material for the next week's show together. They also became good friends and formed a band, the Potter's Wheel. Mortimer began to perform on the show, which was christened Vic Reeves Big Night Out, creating characters such as the Singing Lawyer, Graham Lister, Judge Nutmeg and the Man With the Stick.

The show became successful in South London and eventually outgrew Goldsmiths Tavern, moving in 1988 to the Albany Empire in Deptford. Mortimer soon became an integral part of the performance, providing him with a weekly break from his legal work, which had begun to disillusion him.

Reeves and Mortimer made their television debut on the short-lived 1989 comedy chat show One Hour with Jonathan Ross, in the game show segment known as "Knock down ginger". Later that year, the duo made their first television pilot together, Vic Reeves Big Night Out. The television show remained true to the nightclub act's variety show format. Mortimer took a 10-week break from his legal job to record the series and never returned.

The two later created a one-off pilot for a sitcom called The Weekenders in 1992, followed by the sketch show The Smell of Reeves and Mortimer in 1993, and Shooting Stars, a comedy panel show that first aired in December 1993. After being commissioned, Shooting Stars ran for five series between 1995 and 2002, with a special anniversary edition broadcast in December 2008. A sixth series was broadcast in late 2009, followed by a seventh series in mid-2010, and an eighth in 2011.

In 1999, Reeves and Mortimer appeared in a second sketch show called Bang Bang, It's Reeves and Mortimer. A year later, Mortimer played the part of Jeff Randall in Randall & Hopkirk (Deceased), opposite Reeves as Marty Hopkirk and Emilia Fox as Jeannie Hurst.