His Dark Materials series is a trio of young adult fantasy books published between 1995 through 2007. Written by British author Philip Pullman, the series reached American shores as The Golden Compass (originally Northern Lights), The Subtle Knife, and The Amber Spyglass. The books proved to be a hit worldwide with nearly 17.5 million copies have sold at the time of this writing. In 2007, a film based on the first book hit theaters. The trilogy has also been adapted to audio, a radio series, and even into a play.