Katherine McDonald Wimp stage name Kay Davis (born December 5, 1920) was an American jazz singer best known for her time with the Duke Ellington Orchestra.

Davis went to high school in Evanston, Indiana and studied voice and piano at Northwestern University, where she earned her bachelor's degree in 1942 and her masters in 1943.

In 1944 she joined Duke Ellington's orchestra, where she sang alongside Joya Sherrill and Al Hibbler. She is best known for her wordless vocals in pieces such as "Transblucency" and "On a Turquoise Cloud". She also sang many pieces with lyrics. She is the only person Ellington allowed to reprise Adelaide Hall's famous wordless vocal on "Creole Love Call". Her tenure in Ellington's band coincided with their increasing exposure on film, especially for Universal Pictures. Davis and Billy Strayhorn gave the first performance of Strayhorn's "Lush Life" on November 13, 1948 at Carnegie Hall -- even though the song had been written in the 1930s.

She toured England with Ellington alongside Ray Nance in 1948 and in Europe with the full band in 1950. After leaving Ellington's orchestra in 1950, she married Edward Wimp, and later retired to Florida.