Kathie Kay (born Kathleen Thornhill; 1918 – 2005) was an English singer, known for her radio and television appearances in the Billy Cotton Band Show during the 1950s and 1960s. Her best known recordings are "We Will Make Love" and "A House With Love in It".
I like this spelling better than Kathy because "ie" just seems so much more feminine to me, although both names are pretty great and unique, since Kate and Katie have taken the spotlight for Katherine these days.