Kathleen "Kat" Slater is a fictional character from the BBC soap opera EastEnders, played by Jessie Wallace. She was also played by Kate Peck in a flashback in 2001 and Sumar-Elise Sandford in a flashback in 2018. Kat is the second eldest Slater family sister and first appeared on 18 September 2000. Kat's usual dress is very short skirts and leopard-print tops, with much make-up and heavy fake tan. Her initial stint saw her involved in many storylines, most significantly in a plot twist that sees her supposedly sister Zoe Slater, revealed to be her daughter after she was raped by her uncle Harry Slater as a child. Kat and Zoe's relationship is tested several times, and a feud forms when they compete against each other for the affection of Anthony Trueman. Another key aspect to the character's storylines is her marriage to Alfie Moon, prior to which she became briefly engaged to Andy Hunter ; after Kat jilted Andy on their wedding day, he blackmailed her into sleeping with him in his revenge bid against Alfie and Kat. Kat was absent between November 2004 and May 2005 following Wallace's maternity leave, but returned early to tie in with Zoe’s exit storyline. Kat later left the soap on 25 December 2005.

EastEnders is a British television soap opera created by Julia Smith and Tony Holland which has been broadcast on BBC One since February 1985. Set in the fictional borough of Walford in the East End of London, the programme follows the stories of local residents and their families as they go about their daily lives. Within eight months of the show's original launch, it had reached the number one spot in BARB's television ratings, and has consistently remained among the top-rated series in Britain. Four EastEnders episodes are listed in the all-time top 10 most-watched programmes in the UK, including the number one spot, when over 30 million watched the 1986 Christmas Day episode. EastEnders has been important in the history of British television drama, tackling many subjects that are considered to be controversial or taboo in British culture, and portraying a social life previously unseen on UK mainstream television.