1) There are ten bands and one electronic music producer called Siren.
2) Siren is a drum and bass team founded by Vicious Circle and Ruxspin from Universal Project.
The First is a british blues rock/folk pop band that recorded from 1969-71 headed by Kevin Coyne on vocals and guitar.
The second is an american progressive metal / heavy metal band from Tampa, Florida, formed in 1981. They have a three releases - "Metro-Mercenary" EP in 1984 (self released), "No Place Like Home" in 1986 and "Financial Suicide" in 1989. Read more on Last.fm