Rosalyn Warner (born 1961 in Harwich, Essex; died 4 July 2010 in Sunderland), better known as Mad Cow-Girl, was a British nurse who contested several elections as a candidate for the Official Monster Raving Loony Party. She ran for election to the House of Commons for the Haltemprice and Howden seat in 2008 against incumbent Conservative MP David Davis, where she polled 412 votes (a vote that David Davis won comfortably).