Kay Tse On-kay (Chinese: 謝安琪; born 13 March 1977) is a Hong Kong singer. She is a prominent figure in Hong Kong music and popular culture and was once frequently referred to in the media as a "grass-roots diva" and "goddess". She is known for songs which deal with social issues and the struggle for democracy in Hong Kong.

Tse's main claim to fame was her 2008 song, "Wedding Invitation Street" (囍帖街), which was widely successful and swept many prestigious year-end music awards. This was followed by a string of further hits including "Song of the Year" (年度之歌), Lone Village (獨家村), "Hillwood Road" (山林道) and viral hits such as "The Egg and the Lamb" (雞蛋與羔羊) and "Rashomon" (羅生門). She is considered to be one of the four leading female Cantopop singers of the 2000s–2010s, along with Miriam Yeung, Joey Yung, and Denise Ho.