Jessica Beatrice "J. B." Fletcher is a fictional detective and writer and the main character and protagonist of the American television series Murder, She Wrote. Portrayed by award-winning actress Angela Lansbury, Fletcher is a best-selling author of mystery novels, an English teacher, amateur detective, criminology professor, and congresswoman. In 2004, Fletcher was listed in Bravo's "100 Greatest TV Characters". AOL named her one of the "100 Most Memorable Female TV Characters". The same website listed her among "TV's Smartest Detectives". She was ranked at number six on Sleuth Channel's poll of "America's Top Sleuths". Guinness World Records called her the "most prolific amateur sleuth".

Murder, She Wrote is an American crime drama television series, created by Peter S. Fischer, Richard Levinson and William Link, starring Angela Lansbury, and produced and distributed by Universal Television for the CBS network. The series focuses on the life of Jessica Fletcher, a mystery writer and amateur detective, who becomes involved in solving murders that take place in the fictional town of Cabot Cove, Maine, across the United States, and abroad. The program ran for 12 seasons from September 30, 1984, to May 19, 1996, for a total of 264 episodes and included amongst its recurring cast Tom Bosley, William Windom and Ron Masak, as well as a vast array of guest cast members including Michael Horton, Keith Michell and Julie Adams.