There are 2 artists named "Happy Birthday":
1) Happy Birthday is a Japanese band consisting of Kisa (songwriter, guitar) and Akko (drums) based in Tokyo, Japan. HAPPY BIRTHDAY formed in February 2010 and signed with Sony Music Associated Records Inc. in 2011.
2) Happy Birthday is Kyle Thomas (aka King Tuff), Chris Weisman, and Ruth Garbus. They formed in November 2008 to play one show at the punk-space “Tinderbox” RIP), in their hometown Brattleboro, Vermont. Read more on Last.fm