Simon Posford (born October 28, 1971), better known by his stage name Hallucinogen is an English electronic musician, specializing in psychedelic trance music. His first studio album, Twisted, released in 1995, is considered one of the most influential albums in the genre; the first track "LSD" in particular remains the defining sound of Goa trance to this day. He has toured India several times.

His second album, The Lone Deranger, was released in 1997. A third album, In Dub, was released in 2002.