Kay Hanley (born in Dorchester, Massachusetts on September 11, 1968) is an alternative rock musician. She is best known as the vocalist for the band Letters To Cleo.
Hanley was a member of Letters To Cleo from 1990 to 2000 (the length of the band's existence). She was not only the lead vocalist for the group, but also came up with the band's name (she had a pen pal named Cleo when she was younger). In 1997, she started to work on other projects than the band, starting with a role in the Boston Rock Opera's performance of Jesus Christ Superstar as Mary Magdalene.
In 1999, Hanley made a cameo as herself in the film 10 Things I Hate about You, singing a cover version of Nick Lowe's "Cruel to be Kind" at the movie characters' high school prom.
Towards the end of Letters to Cleo's career, she began performing with her husband and fellow Letters To Cleo member Michael Eisenstein outside of the band. Around the same time, she gave birth to their daughter, Zoe.