Gareth Keenan is a fictional paper salesman on the BBC's comedy The Office, portrayed by Mackenzie Crook. Gareth is a self-important team leader proud of his alleged Lieutenant status in the Territorial Army. He spends his days annoying his co-workers at Wernham Hogg with his rigid enforcement of the rules and sycophantic attitude towards David Brent, whom he views as a friend. Gareth describes his job title as "Assistant Regional Manager", but Brent often corrects this to "Assistant to the Regional Manager". His counterpart on the US series is Dwight Schrute. The character was originally meant to be a tough military character but, after Crook's audition, Ricky Gervais and Stephen Merchant decided to reinterpret the character.

The Office is the original British mockumentary television sitcom first broadcast in the UK on BBC Two on 9 July 2001. Created, written and directed by Ricky Gervais and Stephen Merchant, it follows the day-to-day lives of office employees in the Slough branch of the fictional Wernham Hogg paper company. Gervais also starred in the series as central character David Brent.