There are multiple artists with this name, including a British pop/rock group formed in Glasgow, Scotland, in 1973, and a British boy-band that debuted in 2001, and, after much success, split up in 2005:

1) Blue are a British boy band consisting of four members: Lee Ryan, Duncan James, Antony Costa, and Simon Webbe. The band debuted in 2001, and split up after much success, in 2005. All of the band members pursued solo singing careers alongside other interests.