DCI Jill Marsden is a fictional character in the BBC soap opera EastEnders, played by Sophie Stanton. She made her first appearance on 5 March 2001 investigating the shooting of Phil Mitchell, which was part of the whodunit storyline "Who Shot Phil?". Marsden returned in 2002, 2003 and 2009. She returned on 5 January 2012 for her third whodunit storyline, "Who's Stalking Phil?", departing four months later on 10 May 2012. Marsden returned for two episodes on 17 August 2012 to conclude the latter storyline. On 16 July 2015, she returned for part of the "Who Killed Lucy Beale?" whodunit storyline.

Phil Mitchell is a fictional character from the BBC soap opera EastEnders, played by Steve McFadden. He was introduced to the soap opera on 20 February 1990 and was followed by his brother Grant, sister Sam and mother Peggy. Phil was one of the major characters introduced by executive producer Michael Ferguson, who wanted to bring in some macho male leads. Phil and his brother Grant became popularly known as the Mitchell brothers in the British media, with Phil initially portrayed as the more level-headed of the two thugs. Storylines featuring the Mitchell family dominated the soap opera throughout the 1990s, with Phil serving as one of the show's central characters and protagonists since the 1990s. McFadden temporarily left the series in late 2003, then returned in April 2005 for a brief appearance before making a permanent return in October 2005, and has now overtaken Dot Cotton as the second-longest-serving character in EastEnders, surpassed only by original character Ian Beale. A teenage version of Phil, played by Daniel Delaney, appeared in a flashback episode broadcast on 5 September 2022, which focuses on the Mitchell family in the 1970s.