Louisa Jo Killen was an English folk singer and concertina player who was born as Louis Killen in 1934. She achieved early recognition for helping establish one of the first folk clubs in Newcastle in 1958 and became a professional singer in 1961. After emigrating to the United States in 1967, she worked with the musician Pete Seeger before joining the ensemble The Clancy Brothers in 1971. Killen is famous for being a leading figure in the British folk revival and for introducing the English concertina into the genre. Her discography includes the studio recordings Ballads and Broadsides (1965) and Along the Coaly Tyne (1968), as well as the albums Save the Land (1972) and Show Me the Way (1972) with The Clancy Brothers. In her later years, she worked at the San Francisco Maritime Museum and underwent gender reassignment to become Louisa Jo Killen. She died in 2013.