Born Emma Knight, after her husband, pilot Peter Peel, was lost when his plane went down over the Amazon, and was presumed dead, Emma Peel became a secret agent, a "talented amateur" working alongside professional agent John Steed, together forming a duo unofficially known as The Avengers. Eventually Peter turned up alive and well, prompting Emma to leave Steed and resume married life. Her replacement was Tara King.
Emma Peel was famously played by Diana Rigg, though Elizabeth Shepherd was originally cast in the role. Mrs. Peel replaced Cathy Gale, who had been played by Honor Blackman.
During Peel's tenure the popularity of the Avengers reached new heights, resulting in several comic appearances, including TV Comic, Diana, The Avengers (a one-issue title produced by Mick Anglo), and several annuals. Additionally, the girls' comic "June and School Friend" had a strip showing the adventures of 14 year old Emma Knight, which included showing her designing the one-piece catsuit her adult self would become famous for.
Emma later resurfaced in comics for Eclipse Comics' Steed and Mrs. Peel, written by Grant Morrison and drawn by Ian Gibson, which saw her reunited with both Steed and Tara King. She has also had cameos in several other titles, including Dr. Who Magazine, Kingdom Come, and League of Extraordinary Gentleman: Black Dossier, where she appears pre-marriage as Emma Knight, working alongside James Bond and Bulldog Drummond; by League of Extraordinary Gentlemen: Century 2009 she has been promoted to being the head of MI6, M, and is working alongside all her fellow Avenger girls.