"Partners in Crime" is the first episode of the fourth series of the British science fiction television series Doctor Who. It was broadcast on BBC One on 5 April 2008. The episode reintroduced actor and comedian Catherine Tate as Donna Noble, who had previously appeared in the 2006 Christmas Special "The Runaway Bride". In the episode, Donna and the alien time traveller the Tenth Doctor meet while separately investigating Adipose Industries, a company that has created a revolutionary diet pill. Together, they attempt to stop the death of thousands of people in London after the head of the company, the alien Miss Foster, creates short white aliens made from human body fat. The episode's alien creatures, the Adipose, were created using the software MASSIVE, commonly used for crowd sequences in fantasy and science fiction films.

The fourth series of British science fiction television programme Doctor Who was preceded by the 2007 Christmas special "Voyage of the Damned". Following the special, a regular series of thirteen episodes aired, starting with "Partners in Crime" on 5 April 2008 and ending with "Journey's End" three months later on 5 July 2008. The series incorporates a loose story arc consisting of recurring mentions of the disappearance of various planets and moons.