Kate Victoria "KT" Tunstall (born 23 June 1975) is a Scottish singer-songwriter and musician. She first gained attention with a 2004 live solo performance of her song "Black Horse and the Cherry Tree" on Later... with Jools Holland. She has released eight studio albums internationally: Eye to the Telescope (2004), Drastic Fantastic (2007), Tiger Suit (2010), Invisible Empire // Crescent Moon (2013), Kin (2016), Wax (2018), Nut (2022), and a collaboration album with American musician Suzi Quatro, Face to Face (2023). She has also appeared in two episodes of the comedy series This is Jinsy on Sky Atlantic.

The name of her debut studio album, Eye to the Telescope, was inspired by her childhood experiences at her father's physics laboratory at University of St Andrews. Released in 2004, the album led to her nominations for the Mercury Prize in 2005, a BRIT Award for Best British Live Act and BRIT Award for Best Breakthrough Act in 2006, and a Grammy Award for Best Female Pop Vocal Performance nomination in 2007. She won the BRIT Award for Best British Female Artist and the European Border Breakers Award, both in 2006. The single "Black Horse and the Cherry Tree" was given the Q Magazine Award for Best Track in 2005, and "Suddenly I See" won the Ivor Novello Award for Best Song in 2006. "Suddenly I See" became a popular hit and has been featured in The Devil Wears Prada, Blind Dating, Ugly Betty, Grey's Anatomy and Love, Rosie; Thrillville, and as a campaign song on the Hillary Clinton 2008 presidential campaign.

Tunstall has written music and songs for film soundtracks including "Boy" for The Kid, "Miracle" for Winter's Tale, "We Could Be Kings" for Million Dollar Arm; "Float", "Strange Sight" and "1000 Years" for Tinker Bell and the Legend of the NeverBeast; "Fit In" for About Ray; and "Bad Moms (Suite)", "Enough is Enough (Suite)" and "Get Your Tits Up (Suite)" for Bad Moms.