John Stuart Ellis (born 4 June 1955) is a British theatre and television actor from London, best known for his portrayal of villainous prison officer Jim Fenner in the TV series Bad Girls.
His first major part since Bad Girls came in summer 2006; Ellis appeared in several episodes of ITV drama Where the Heart Is as businessman Robert Ashford.
In 1994 Ellis played the part of Eddie Barton, a senior HM Customs & Excise Investigation Division officer based at Heathrow Airport who had to retire through ill health caused by motor neurone disease in all seven episodes of series one of The Knock.
In late 2005 Ellis starred in A Few Good Men at London's Theatre Royal, Haymarket, playing opposite Rob Lowe, John Barrowman and Suranne Jones.
In 2016 Jack starred as Warden Stammas in the theatre production of Stephen King's The Shawshank Redemption, playing alongside Paul Nicholls and Ben Onwukwe.