Infant Sorrow is a fictitious band appearing in Forgetting Sarah Marshall and Get Him to the Greek. Russell Brand doesn’t just play the role of the band’s front man in the films, he does all the vocals and most of the vocal arrangements for the various songs found in the movies. The soundtracks for both movies also credits Brand as a writer.

Jason Segel starred in Forgetting Sarah Marshall and co-wrote both films and created all the characters, including the Infant Sorrow band. The name of the band as well as Russell Brand’s character, Aldous Snow, is based upon the short poem by William Blake of the same name.