To start off the list, we'll first look at a composer responsible for some of the most iconic film music of all-time, but who is still a relative unknown outside of film fans. A career collaborator of Darren Aronofsky, Clint Mansell has scored every one of his movies so far, beginning with Aronofsky's debut film, Pi in 1998. In 2000, for Aronofsky's Requiem for a Dream, Mansell composed a score so brilliant and instantly iconic that, in many ways, it has transcended the world of film music and become something that seemingly everyone recognizes. Lux Aeterna, as the main theme is called, has since been used in countless trailers and commercials, and is generally considered one of the best pieces of film music so far this century. A good score is essential in helping to convey the emotions and overall tone of a movie, and Clint Mansell is one of the best film composers working today, having gone on to create incredible scores for films such as The Fountain and Moon. Even so, he still remains sadly under-appreciated.