Alison Steadman (born 26 August 1946) is an English actor. She won the 1991 National Society of Film Critics Award for Best Actress for the Mike Leigh (her husband 1973-2001) film Life is Sweet, and the 1993 Olivier Award for Best Actress for her role as Mari in the original production of The Rise and Fall of Little Voice. In a 2007 Channel 4 poll, the "50 Greatest Actors" voted for by other actors, she was ranked No. 42.

Steadman made her professional stage debut in 1968 and went on to establish her career in Mike Leigh's 1970s TV plays Nuts in May (1976) and Abigail's Party (1977). She received BAFTA TV Award nominations for the 1986 BBC serial The Singing Detective, and in 2001 for the ITV drama series Fat Friends (2000–05). Other television roles include Pride and Prejudice (1995), Gavin & Stacey (2007–10, 2019) and Orphan Black (2015–16). Her other film appearances include A Private Function (1984), Clockwise (1986), Shirley Valentine (1989), Topsy Turvy (1999), and The Life and Death of Peter Sellers (2004).