Jay Brown (also Mitchell) is a fictional character from the BBC soap opera EastEnders, played by Jamie Borthwick. He made his first appearance on 14 December 2006. Borthwick was suspended from the soap in June 2025 for using unacceptable language whilst participating in Strictly Come Dancing the previous year, and was subsequently axed in September 2025. His final appearance aired on 19 August 2025.

Jay's storylines since joining the programme have included being part of a gang, coping with the death of his father Jase Dyer (Stephen Lord), being orphaned by age 14 which results in his going into foster care and then being taken care of by the Mitchell family, as well as maturing from a wayward teen, becoming a brotherlike figure to Ben Mitchell (Charlie Jones/Joshua Pascoe/Harry Reid/Max Bowden), a relationship with Abi Branning (Lorna Fitzgerald), helping Ben cover up the murder of Heather Trott (Cheryl Fergison), being arrested for having indecent images of a child on his mobile phone after discovering his girlfriend Linzi Bragg (Amy-Leigh Hickman) is below the age of consent, drug dealing and developing a drug habit by taking cocaine. In August 2017, in a two-hander episode between Phil and Jay, Jay finds out that Phil accidentally killed his biological father, a homeless man who was at the car lot the night that Phil set it alight in 1994, however, this is later revealed to be a lie. Jay later embarks on relationships with Ruby Allen (Louisa Lytton), Lola Pearce (Danielle Harold) and Honey Mitchell (Emma Barton). Jay eventually reunites with Lola and they marry in January 2023, however Lola dies in May 2023 from a brain tumour. Jay develops an addiction to ketamine in the aftermath of Lola's death.

Borthwick was 12 years old when he joined the cast of EastEnders. He attended three auditions, followed by a screen test, after which he was offered the part of Jay. Originally a recurring character, Jay was considered a regular from July 2007. He was involved in a minor racism storyline, where he called another character, Yolande Trueman (Angela Wynter), a "black cow". EastEnders executive producer Diederick Santer said this was inspired by the race row in Channel 4's reality show, Celebrity Big Brother, commenting: "The Celebrity Big Brother race row kicked off as I took charge of my first scripts. I thought it was fascinating because it showed there was a real need for a debate about race in Britain. [Big Brother] didn't do it particularly well, so I thought it could be something EastEnders should do. Our stuff won't be overly moralistic or preachy but it will tackle this serious issue head on." Another controversial storyline saw Jay get involved with a gang of youths, ending with him being stabbed in the thigh. A BBC spokesperson said "This is easily one of the most shocking and controversial storylines EastEnders has ever done. It is not a decision bosses have taken lightly, but it is an issue that is top of the news agenda. [...] We're going to tread very carefully — it won't be gratuitous. The plan is to screen the episodes in the usual slots before the watershed. Hopefully by showing the suffering that gang violence can cause, some people may think twice about getting involved."

In December 2015, it was announced that one of the biggest storylines of 2016 would be for Jay, and it was speculated that February 2016's introduction of a new love interest for Jay, Linzi Bragg (Amy-Leigh Hickman), would be linked to this storyline. The episode airing on 18 April 2016 reveals that Linzi is, unbeknownst to Jay, an underage schoolgirl. It was said that Jay would face "severe consequences".

The storyline and Borthwick's performance were praised by viewers on social media. Laura-Jayne Tyler of Inside Soap stated, "EastEnders Jamie Borthwick is the undisputed 'bullseye' star of the week. His performance as Jay was simply outstanding as the fella paid the price for his relationship with Linzi. It's a storyline that tested allegiances, divided a community – and won our vote as one of the best plots of the year. Truly exceptional." Hannah Verdier from The Guardian called it "the most unsavoury of storylines".

In June 2025, Borthwick was suspended from EastEnders by the BBC after a backstage video from the twenty-second series of Strictly Come Dancing in November 2024 surfaced, showing him referring to the inhabitants of Blackpool by using ableist language considered derogatory toward disabled individuals. The BBC described his language as "entirely unacceptable" and said it did not reflect their values or standards. He issued a public apology in a statement to The Sun on Sunday, expressing regret for his words and acknowledging the offence they had caused. In September 2025, it was announced that Borthwick had been axed from the soap after 19 years and would therefore not be returning to film exit scenes. His final appearance aired on 19 August 2025.

Jay is mentioned in 2006 when his dying grandmother, Evie Brown (Marji Campi) tells his grandfather Bert Atkinson (Dave Hill) that he has a grandson. Their daughter, Karen, is Jay's mother who died from breast cancer. Jay appears after Evie's funeral, when he is taken to live with Bert in Walford, per Evie's wishes. Jay is a troublesome youth: he steals, breaks into Pauline Fowler's (Wendy Richard) house, and offends Yolande Trueman (Angela Wynter) with a racist slur to impress his peers. When Jay's father Jase Dyer (Stephen Lord) arrives, Bert leaves to allow Jay and Jase to bond. Jay continues getting into trouble, becoming involved with a gang of older boys, known as the E20 crew, led by Tegs Teague (Ben Smith). Jay helps them shoplift, and they give him a knife. The gang terrorises Dot Branning (June Brown) and Jay steals her keys so they can break into her house. The gang orders Jay to throw a brick through Dot's window, but realising it is wrong, Jay refuses and is rejected from the gang. Tegs later confronts Jay and a fight ensues, with Jay being stabbed in the leg. Tegs is arrested and his mother Tina Teague (Kerry Ann White) tries to threaten Jay from testifying against her son at his trial. However, she is scared off by Jase's girlfriend Dawn Swann (Kara Tointon). Jay gives evidence at the trial and Tegs is sentenced to two years in a Young Offenders Institute.

Jay and Jase try to flee Walford when Jase double-crosses a football firm but Dawn stops their departure by setting a date for her and Jase's wedding. The firm, led by Terry Bates (Nicholas Ball), holds Jay hostage to get revenge on Jase. Jase is able to save Jay with the help from his friend Billy Mitchell (Perry Fenwick), but ends up getting beaten to death by Terry's goons and Billy – too frightened to intervene – leaves Jase to die. Jay accuses Dawn of causing his father's death and goes into care to get away from her. Jay is later fostered by Billy, who is wracked with guilt for not saving Jase from the gang. Jay's behaviour worsens when he plans an arson attack on Dawn, but Billy is able to stop him and Jay eventually makes amends with Dawn. Jay and Billy move into a flat with Janine Butcher (Charlie Brooks), who tries to get rid of Jay by stealing and blaming it on him. Feeling unwanted, Jay befriends Marissa Moore (Finn Atkins), who works at a brothel, and they plan to run away together. When Marissa backs out, Jay runs away alone and sleeps rough, until Billy convinces him to move back in. Terry's trial for Jase's murder approaches and Jay is furious to learn that, rather than attempting to help Jase, Billy hid to save himself. Terry's wife, Viv Bates (Dido Miles), threatens to hurt Jay if Billy testifies. Jay is taken hostage by Terry's firm as a security measure, and Billy risks his own life to save him. Billy and Jay are both rescued by the police and Billy testifies, which results in Terry receiving life imprisonment for murder, partially redeeming himself in the eyes of Jay.