James Willmott-Brown (also credited as Willmott-Brown and Mr Willmott-Brown) is a fictional character from the BBC soap opera EastEnders, played by William Boyde. The character originally appeared in Albert Square from 1986 to 1989, where he established the square's second pub – "The Dagmar" – and instigated a feud with his business rival Den Watts (Leslie Grantham). Willmott-Brown then developed a romantic obsession with his employee Kathy Beale (Gillian Taylforth), which sparked the events of the character raping her in 1988.

Following his imprisonment for Kathy's rape, Willmott-Brown made a brief comeback in 1992 after he moved back into Albert Square; however, he was forced to leave by Kathy's former husband Pete (Peter Dean) just weeks later. After an absence of 25 years, Willmott-Brown returned on 22 September 2017 as the show's hidden main antagonist upon being revealed to be the boss of Max Branning (Jake Wood) in their vengeful plot to destroy the square; with Willmott-Brown serving as the true mastermind behind the events in Max's revenge story arc carried out by his company, Weyland & Co. The character departed once again on 28 December 2017 after his scheme to recoup his relationship with Kathy by controlling the Square had ultimately failed, and he was left bedridden and disowned by both his son and daughter for his actions.

In 1988, the character of Willmott-Brown raped Kathy Beale (Gillian Taylforth) in a "prolific and controversial [...] deplorable" rape storyline. Taylforth was apprehensive about the storyline when it was pitched to her, commenting that she "didn't think it was a great idea at first" as her character had already been raped and "didn't think Wilmott-Brown was a very likely rapist." Taylforth said she "loved working" with Boyde, saying he played the part "brilliantly" as well as it being his own idea "to step up Wilmott-Brown's drinking in order for the rape to make some sense."

Boyde departed the role in 1989, when his character was found guilty of rape. The storyline "had massive repercussions for the residents of Walford", notably for Den Watts (Leslie Grantham), as the storyline resulted in his imprisonment for "taking the rap" over The Dagmar fire caused by The Firm. Boyde returned in 1992 for a short stint, which saw Willmott-Brown "try and reintegrate in Walford" but a "lack of remorse saw him receive significant backlash."

Boyde reprised his role as Willmott-Brown in September 2017 and the actor expressed his delight at returning to the serial. Willmott-Brown returns to overpower Albert Square, the show's setting, and destroy "everything and anyone in their way". Duncan Lindsay of the Metro reported that his return storyline would centre around "power, control, money and revenge" as well as confronting Kathy, who Willmott-Brown cites as the person who destroyed his life.

The characters of Fi Browning (Lisa Faulkner) and Josh Hemmings (Eddie Eyre), who joined the show in 2017, were revealed as Willmott-Brown's children. Faulkner's character was explained as Willmott-Brown's daughter, Sophie Willmott-Brown, who appeared in the serial in 1987 and 1992 as a child, portrayed by Natasha Knight. Adam Astill was recast in the role of Willmott-Brown's son, Luke Willmott-Brown, (now Luke Browning), who previously appeared, portrayed by Henry Povey, alongside his sister. The build-up to Willmott-Brown's return began when Max Branning (Jake Wood) returned to the serial after being falsely imprisoned for the murder of Lucy Beale (Hetti Bywater). Max agrees with Willmott-Brown's plans as he is unaware of his past and understands that he is a "wronged man". Of his return, Boyde said: "I'm delighted to immerse myself once more in the fascinating world of soap land." Willmott-Brown made an unannounced departure on 28 December 2017, alongside Fi and brother-in-law Hugo Browning (Simon Williams) at the conclusion of their storyline.

James Willmott-Brown, an ex-army officer, arrives in Albert Square in March 1986 as area manager for 'Luxford and Copley', the brewery that owns The Queen Victoria public house. Willmott-Brown decides to move to the square and buys Debbie Wilkins's (Shirley Cheriton) house at 43 Albert Square when she sells it, following fiancé Andy O'Brien's (Ross Davidson) death. He and Debbie date briefly but it doesn't last and Pat Wicks (Pam St Clement) also tries to seduce him unsuccessfully. During the early years, he is friendly with Colin Russell (Michael Cashman).

Willmott-Brown gives up his job as brewery manager and buys a disused pub on Turpin Road, refurbishing it as a wine bar and names it "The Dagmar". Local publican Den Watts (Leslie Grantham) is unhappy about the competition and is disgusted to learn that his estranged wife, Angie (Anita Dobson), is manageress. Willmott-Brown also allows Angie and her daughter, Sharon (Letitia Dean), to live in the flat above. The Dagmar opens for business and both Willmott-Brown and Den compete for best decorated pub in 'The London In Bloom' competition and in a five-a-side football match, and constantly try to poach each other's staff. The following year, the Dagmar begins to lose business as the residents of Walford never really take to the upper-class establishment and Willmott-Brown has competition from The Queen Victoria and Strokes winebar, which Den takes over after giving up tenancy of The Queen Vic. At this point, Gregory Mantel (Pavel Douglas) arrives and he is a member of the criminal organisation known as The Firm. Mantel demands that Willmott-Brown allow his company, 'Walford Investments', to buy into the business. Willmott-Brown refuses, and as a result, none of his creditors will trade with him and the business suffers even more. This is escalated when Willmott-Brown learns that Den is in league with the Firm and reports him to the police for shady dealings at Strokes wine bar but Simon Wicks (Nick Berry), barman at The Dagmar, overhears Willmott-Brown talking to the police and tells Den. When the residents learn that Willmott-Brown has informed the police, he loses all his customers, pushing Willmott-Brown to financial ruin. This makes him frantic and his behaviour becomes erratic.