Billy Mitchell is a fictional character from the BBC soap opera EastEnders, played by Perry Fenwick, who made his first appearance on 2 November 1998.

Billy was originally introduced by producer Matthew Robinson as a guest character, facilitating the introduction of Jamie Mitchell (Jack Ryder) to the show.

Billy's other major story lines have seen him involved in criminal activities with both Phil and his brother Grant Mitchell (Ross Kemp); working for Steve Owen (Martin Kemp); and being blackmailed by Dan Sullivan (Craig Fairbrass) to gain leverage against Steve and Phil, leading to Dan kidnapping Mel Owen (Tamzin Outhwaite); his complicated relationship with Janine Butcher (Charlie Brooks); marrying Little Mo after she overcomes her abusive husband Trevor Morgan (Alex Ferns); a subsequent incident where Little Mo gets raped by Graham Foster (Alex McSweeney) and struggling to cope with raising their son Freddie; a feud with Andy Hunter (Michael Higgs) and attempting with Minty Peterson (Cliff Parisi) to stop Andy from marrying Phil and Grant's sister, Sam Mitchell (Kim Medcalf); getting employed by Johnny Allen (Billy Murray); having a close friendship with Jase Dyer (Stephen Lord) before witnessing the latter's brutal death at the hands of his gang boss Terry Bates (Nicholas Ball); becoming the guardian of Jase's son Jay Brown (Jamie Borthwick) up to the point of becoming his surrogate father; starting a short-lived romance with Jean Slater (Gillian Wright); reuniting with his former girlfriend Julie Perkins (Cathy Murphy) and discovering that their deceased son had a daughter Lola Pearce (Danielle Harold); and developing a romantic obsession with Lucy Beale (Hetti Bywater).

After learning that Phil and Grant plan to do a robbery that is set to be botched, Billy alerts their sister Sam Mitchell (Danniella Westbrook) and her boyfriend Beppe di Marco (Michael Greco) about their plans – which sparks a police chase on the Mitchell Brothers that results in them driving into the River Thames; Phil is rescued while Grant is presumed dead.

Soon afterwards, Phil discharges himself from hospital and frames his friend-turned-enemy Dan Sullivan (Craig Fairbrass) for the crime – even though his ex-girlfriend Lisa Fowler (Lucy Benjamin) was responsible for the shooting.

Billy manages to help Steve and Phil rescue Mel, but they fail to stop Dan from fleeing Walford with the money.

In light of Dan's departure and Mel's kidnapping ordeal, Billy finds himself further embroiled in Phil and Steve's rivalry – up to the point where they each deem him distrustful.

Their feud ultimately ends with Steve kidnapping Phil's infant daughter, Louise Fowler to flee Walford with Mel and exact his last-ditch revenge.

By the time his relationship with Jamie is mended, Billy has become the sworn enemy of Little Mo's husband, Trevor Morgan (Alex Ferns) – because of the torment and abuse the latter imposed on her for the majority of their marriage.

Their happiness is virtually compromised when Jamie gets struck by a car driven by his best-friend and Mark's brother, Martin Fowler (James Alexandrou).

Billy and Little Mo reunite, but their marriage eventually ends after he admits to being unable to love Freddie due to comparing him with Graham.

The relationship prospers, despite initial disapproval from Honey's father, Jack Edwards (Nicky Henson), who takes time to accept Billy.

Their wedding is postponed when Honey is hospitalised, they reschedule, however the second ceremony goes awry because of a practical joke played on Billy during his stag night.

His birth is traumatic, as Honey goes into labour after being caught in a violent siege: she is assaulted by a member of a football firm led by local gang boss Terry Bates (Nicholas Ball).

When Billy stops a man from pestering Jean Slater (Gillian Wright) at a club, she brands him a hero and they end up having sex.

Lola's announcement that she is pregnant leads to Billy going back to his criminal ways to provide for his great-grandchild —stealing from Janine and trading stolen goods and forgeries for Derek Branning (Jamie Foreman).

Billy grows tired of Lola's troublesome behaviour and gives her a curfew and electronic tag After which he can focus on being an Olympic Torch bearer, of which he learnt several months earlier.

Billy is over-protective of Lola when she starts a relationship with Peter Beale (Ben Hardy), but eventually becomes friends with him and realises that he is a good man.

Billy was involved in an abuse storyline with his nephew, Jamie Mitchell (Jack Ryder), causing the actor to be "harangued" by strangers in public.

Her pregnancy was the start of an ongoing storyline about Down syndrome (DS) as, in September 2006, Honey and Billy's baby Janet was diagnosed with the disorder shortly after her birth.

Real parents with children who have Down Syndrome were approached to act as consultants in the making of the storyline, meeting with writers and the actors who play Billy and Honey.

The programme makers' main priority was to show the reality of having a child with the condition, "with all of its positives and negatives" and to "create awareness among thousands of people who know very little about Down syndrome, who might have out-dated or prejudiced views."

[8] Sue Jacob, a teacher at the Royal College of Midwives (RCM), said EastEnders presented a "poor picture of midwifery practice".

The midwife would also have been open and honest and said 'We need to get the baby checked out and we will get your partner' [...] What the soaps do is set scenes which prompt people to talk about things which are affecting their lives.

[9] The BBC responded by saying, "EastEnders has undertaken a great deal of research to script the storyline of Billy and Honey giving birth to their baby daughter.

In relation to some particular points raised, Honey was not denied an epidural — she made the choice to put herself out of reach of communicating effectively with the midwife by locking herself in the bathroom.

"[8] In 2010, storylines show Billy receiving a letter from the care home he stayed in as a child, and a character from his past, Julie Perkins (Cathy Murphy) arrives in the series.

It was reported that Billy and Julie would be shocked to learn of Lola's existence, not knowing the son they once gave up for adoption had a daughter, but would decide to track her down and find her living in a care home.

[4] According to Methven, "The turning point for Billy's popularity came when viewers learned his nasty streak was a result of him having been abused and bullied while growing up in a children's home"[4] In 2020, Sara Wallis and Ian Hyland from The Daily Mirror placed Billy 49th on their ranked list of the Best EastEnders characters of all time, calling him a "Perpetual loser in life and love" who is portrayed "superbly" by Fenwick.

[13] In 2024, following the scenes where Billy discusses how his father neglected him, Chloe Timms from Inside Soap wrote "Perry Fenwick has been out of this world.