Sam Mitchell (also Butcher and Hunter) is a fictional character from the BBC soap opera EastEnders. The third member of the Mitchell family to appear on the soap, Sam was introduced as a 15-year-old schoolgirl in July 1990, originally played by Danniella Westbrook. Westbrook left in 1993, but Sam reappeared from 1995 to 1996 and from 1999 to 2000. In both stints, Sam was written out earlier than the producers intended due to off-screen controversies surrounding Westbrook. In January 2002, Sam was introduced for a fourth time, but the role was recast to Kim Medcalf, who stayed in the role until November 2005. Diederick Santer later decided to reintroduce Sam for a brief stint in 2009 and opted to bring Westbrook back. Westbrook briefly reprised the role once again in 2016 for the funeral of Sam's mother Peggy Mitchell (Barbara Windsor). In January 2022, it was announced that Sam would be returning to the show, this time played by Medcalf again. Medcalf’s return scenes aired on 18 April 2022. Medcalf took an extended break from the show in 2023, with Sam departing on 13 April 2023 and returning seven months later on 21 November 2023. On 18 January 2024, Sam made an unannounced departure from the show following Medcalf's decision to leave indefinitely. On 13 February 2025, Sam appeared in flashback episode with Laila Murphy portraying her again. Medcalf will reprise the role for a short stint beginning December of the same year.

At first Sam was initially portrayed as a young naïve girl who had often been relied upon less by her mother Peggy in contrast to Sam's two older brothers Phil (Steve McFadden) and Grant (Ross Kemp) on frequent occasions. However, as time went on, Sam gradually evolved into becoming a more charismatic and headstrong woman with a penchant for dating the wrong men and a determination to be taken more seriously.

Her storylines involved an elopement with established character Ricky Butcher (Sid Owen); a competitive love triangle with Ricky and his second wife Bianca Jackson (Patsy Palmer); an on-off quarrel with sister-in-law Sharon Watts (Letitia Dean); having sex with various antagonists such as Phil's archenemy Steve Owen (Martin Kemp) and wife-beater Trevor Morgan (Alex Ferns); feuding with the rival Watts family that involves Sam sleeping with Sharon's half-brother Dennis Rickman (Nigel Harman) and later getting conned by their illegitimate father Den Watts (Leslie Grantham); getting seduced in a relationship with crime boss Andy Hunter (Michael Higgs) and later marrying him; being betrayed by family lawyer Marcus Christie (Stephen Churchett) when he collaborates with Den's plan to bankrupt the Mitchell Empire; a platonic friendship with Phil's friend Minty Peterson (Cliff Parisi); a lengthy feud with Den's widow Chrissie (Tracy-Ann Oberman) that culminates in the latter framing Sam for Den's murder; an affair with local club owner Jack Branning (Scott Maslen) that leads to the birth of their son Ricky Branning (Henri Charles/Frankie Day); becoming a suspect in the murder of her uncle Archie (Larry Lamb); feuds with Kat Slater (Jessie Wallace) and Denise Fox (Diane Parish); scheming with Phil's rival Jonah Tyler (Mark Mooney) in taking over the family assets; discovering that her son Ricky is becoming a father at twelve years old; and publicly revealing Phil’s one-night stand with Emma Harding (Patsy Kensit), which leads to her departure from the show.

The character Sam Mitchell was introduced in July 1990 by EastEnders' executive producer Michael Ferguson as the young sister of the Mitchell brothers, Phil (Steve McFadden) and Grant (Ross Kemp). Sam was one of several characters introduced by the producer in the summer of 1990. Others included Eddie Royle (Michael Melia), and three generations of the Tavernier family.

As the casting team had successfully cast the actors who were playing Sam's brothers, they already knew what facial attributes they needed for Sam to create a similar family resemblance. Producer Corinne Hollingworth has commented, "we'd decided on Steve [McFadden] and Ross [Kemp] and we knew the sort of round, open face we needed. We saw Danniella (Westbrook) first and liked her, then saw some others, but came back to her." The actress, a graduate of the Sylvia Young Theatre School, had already appeared in the soap aged 11, as an extra who rollerskated across the soap's fictional setting of Albert Square in front of the characters Den and Angie Watts. At the time, Westbrook's local paper ran a story on her with the punchline, "who knows, one day she might be the show's star". Eighty girls auditioned for the part of Sam, but these eighty were eventually whittled down to four. On her final casting callback, Westbrook bumped into actors Michelle Gayle and Sid Owen, who were already on the EastEnders cast as Hattie Tavernier and Ricky Butcher respectively. Westbrook already knew Gayle, whose character was to be Sam's screen best friend, and she introduced her to Owen, whose character was scripted to be Sam's boyfriend. According to Westbrook, she liked Owen right from the start and was amused by his response of "You're a bit of alright. You can be Sam!". On Westbrook's last audition, she and the other hopefuls were forced to stand for a lengthy period in front of a panel of the show's producers, directors, and writers while they continuously compared images of the auditionees to images of Kemp and McFadden, looking for a resemblance. Westbrook was given the part. She has commented, "they told me they were looking for someone bright and bubbly, who could be the sister of Phil and Grant, and my round face fitted." In the character's first scene, Sam walked past Ricky Butcher and gave him a "flirty backward glance", causing him to walk into a lamp-post. Westbrook was initially given a three-month contract with the soap, but halfway through her contract the producers extended it as they felt "the character of Sam had gelled well with the others and they wanted to include her in more storylines".

Westbrook has said that the cast and crew became like a second family to her, with the roles in the soap mirroring their relationships off-screen. In her autobiography she comments, "Sid [Owen] and I became very close [...] we were as thick as thieves. When we weren't shooting together we'd hang out [...] Once Sid and I got so bored hanging around on set that we decided to take the milk float for a spin around Albert Square, but Sid drove it too fast and turned it over [...] we couldn't stop laughing, but the producers didn't seem to share our amusement. We were seriously told off that day." She has described other actors like Michelle Gayle, Letitia Dean, Adam Woodyatt and Nick Berry like brothers and sisters, and has said she was very close to older cast members such as June Brown, Wendy Richard, Mike Reid and Gillian Taylforth. She has also revealed that her off-screen relationship with actors McFadden and Kemp mirrored her character's on-screen one: "In the soap they were my older brothers, always looking out for me, making sure I didn't get into trouble, and off set they were exactly the same."

The character has been described by Hilary Kingsley, author the EastEnders Handbook, as a "tease [...] a pretty girl who thinks she can get anything she wants, thanks to her own brand of sexy wheedling." She adds that Sam is "a lot sharper than her brothers [...] and contrives to do just what she wants in the face of their attempts to stand in for their dead father [...] Sam loves excitement and doesn't frighten easily. She's a user, able to get almost anyone to do what she wants." Kate Lock, author of EastEnders Who's Who, has described Sam as "Headstrong, streetwise and pretty [...] a chip off the old Mitchell block, though her methods of manipulation are marginally more subtle than [her brothers]. One bat of a sooty eyelash is enough to charm most men into submission and she can wind doting mum Peggy round her little finger [...] [when] she returned to the Square [in 1999], Sam had lost her kittenish cuteness and hardened up, becoming more EastEnd moll than Barbie doll."

Describing the character in 2002, actress Kim Medcalf said, "She wears her heart on her sleeve. She so wants to settle down that she doesn't select men well. She goes for people too quickly. She likes the danger aspect – the thrill of the chase. She loves guys with a dangerous edge [...] She's had a tough upbringing. She didn't know her dad and her older brothers bossed her around. She needed to find herself and has done it by being independent and going away. She's headstrong and has a definite independent streak." She has added that Sam has a problem with women, as she "finds it quite hard to relate".