Kathryn "Kathy" Valentine (born January 7, 1959, Austin, Texas) is an American bass guitarist, best known for her work in The Go-Go's.
Valentine began playing at age 16 in her hometown of Austin, and joined a fledgling Girlschool in London, England in 1975. In 1978, Valentine was a member of the Austin punk band, the Violators, alongside Carla Olson, Jesse Sublett and Marilyn Dean. The band played at Austin's first punk club, Raul's. In late 1978 Valentine relocated to Los Angeles, California and co-founded The Textones with Carla Olson.
She joined the Go-Go's on New Year's Eve 1980, as a substitute for an ailing bassist, but was asked to remain as a permanent member shortly thereafter. She wrote "Can't Stop the World" on the Go-Go's debut album, and co-wrote the hit singles, "Vacation", "Head over Heels", and "The Whole World Lost Its Head" which appeared on subsequent releases. After the Go-Go's disbanded for the first time in 1985, Valentine played guitar in the World's Cutest Killers with former Girlschool guitarist Kelly Johnson.