Jack Branning is a fictional character from the BBC soap opera EastEnders, played by Scott Maslen. He made his first appearance on 29 October 2007. He is the youngest child of Jim (John Bardon) and Reenie Branning (Joy Graham) and the brother of April Branning (Debbie Arnold), Carol Jackson (Lindsey Coulson), Derek (Jamie Foreman), Suzy (Maggie O'Neill) and Max Branning (Jake Wood). The character was introduced to the show during a period when EastEnders was being routinely criticised in the media for its reliance on resurrecting old characters. The casting of Maslen provoked some controversy, being the first time an actor had been poached from one mainstream soap to another. It was quickly established that Jack is a morally ambiguous character with a murky past in the police force resulting in the paralysis of his young daughter, Penny (Mia McKenna-Bruce). On 1 July 2019, Maslen filmed his 1,000th episode as Jack.

Maslen took a two-month break from the role in October 2010 to participate in the 2010 series of Strictly Come Dancing, returning in December 2010. Maslen made an indefinite departure from the role on 15 October 2013 after six years on the show. Having turned down a chance to return to the role in April 2015, Jack made a previously unannounced return on 24 December 2015, before leaving once again on 1 January 2016. Maslen returned to filming during the same month and Jack returned on-screen on 1 March 2016.

Jack has been involved in several key storylines and has embarked on feuds with his brothers, Max Branning (Jake Wood) and Derek Branning (Jamie Foreman), as well as Phil Mitchell (Steve McFadden), Sean Slater (Robert Kazinsky), Janine Butcher (Charlie Brooks), Michael Moon (Steve John Shepherd), Charlie Cotton (Declan Bennett), Hunter Owen (Charlie Winter), Ray Kelly (Sean Mahon), Ravi Gulati (Aaron Thiara) and Harry Mitchell (Elijah Holloway). Since returning in 2016, his storylines have included reuniting with Ronnie Mitchell (Samantha Womack), gaining custody of his son Ricky Mitchell (Henri Charles/Frankie Day), finding out Ronnie had drowned on their wedding day and his subsequent grief over her death, a custody battle with Charlie Cotton (Declan Bennett) over his stepson Matthew Mitchell Cotton, supporting his great-niece Tiffany Butcher (Maisie Smith) over her rape and confronting her attacker, rejoining the police force, relationships with Mel Owen (Tamzin Outhwaite) and Denise Fox (Diane Parish), discovering that Amy has been self-harming, dealing with his son Ricky becoming a father at twelve-years-old, an affair with Stacey Slater (Lacey Turner), helping The Six conceal their involvement in the murder of Keanu Taylor (Danny Walters), dealing with Amy being temporarily paralysed after a crush at Peggy's Nightclub, framing Penny (now Kitty Castledine) for causing the crush, and being blackmailed by Harry Mitchell (Elijah Holloway), splitting and being divorced from Denise but later reconciling, and unintentionally shooting Zoe Slater (Michelle Ryan).

Jack Branning was one of several new characters to join the EastEnders cast in the second half of 2007. At a time when the show was undergoing media criticism for its resurrection of old characters, John Yorke, the BBC's controller of drama production, defended the show's ability to create interesting, new characters. He praised the show's executive producer Diederick Santer for his development of new, "strong characters", including Jack Branning and Roxy (Rita Simons) and Ronnie Mitchell (Samantha Womack). Speaking of this new wave of characters, he stated: "It feels like a new dynasty is emerging, which is important."

Prior to his introduction in October 2007, the character was referred to once, a week before his arrival. He is a member of the soap's Branning family; his sister Carol first appeared in the serial in 1993, while father Jim had debuted in 1996, and Jack's brother Max and his own family were introduced in June 2006.

Scott Maslen was cast in the role of Jack. Previously best known for his role as DS Phil Hunter in ITV police drama The Bill, the media were quick to pick up on the fact his new role was notably similar – with TV critic Jane Simon sarcastically commenting: "What a relief it must be for actor Scott Maslen to get a role that allows him to show off his incredible versatility." Maslen himself pointed out that the character of Jack was actually higher ranking than Phil Hunter, joking: "I've been promoted from playing a DS in Sun Hill!" Maslen's casting marked the first time an established actor had been poached from one mainstream soap to another. Speaking for the first time about his new role, Maslen said: "I was very sad to leave The Bill but after five years I wanted to explore new opportunities. The Bill afforded me some fantastic storylines. I'm really looking forward to playing Jack. He's an extremely competitive man who likes to win in business and in pleasure!"

Upon announcing his casting, Maslen described the character of Jack as "an extremely competitive man who always likes to win in business and in pleasure". He mentioned that there would be an "instant attraction" between Jack and fellow newcomer Ronnie Mitchell, and explained that he already had a longstanding friendship with Samantha Womack who plays Ronnie, having known her since he was 16 years old, and being godfather to her children.

The relationship between the two characters developed quickly from friendship to romance, with Womack commenting that due to her friendship with Maslen; "Our first kissing scene felt really uncomfortable, it was terrible, but we're over it now." Several media publications commented on the fact that the attraction between the two characters had been obvious, and bound to develop into more than a professional relationship.