Donald Jay Fagen (born January 10, 1948) is an American musician and songwriter, best known as the co-founder, lead singer, and the principal songwriter (along with partner Walter Becker) of Steely Dan.

Fagen is known for his use of complex jazz harmonies, elaborate arrangements, and exacting attention to detail and launched his successful, if sporadic solo career in 1982.Fagen penned a group of songs based on his experiences as a young man in 1950's America, and the resulting album, The Nightfly, was released in 1982, and is one of the first albums to be recorded entirely digitally.

The album has been certified platinum by the RIAA. After a quiet time musically (he is reported to have suffered from writers block) for the rest of the 80s he returned in 1993 with Kamakiriad, which is a conceptual album based on a car journey.

The album was produced by Walter Becker and represented the first collaboration between the two since Gaucho.This collaboration reignited Steely Dan and they released two more albums, the Grammy award winning "Two Against Nature" in 2000, and "Everything Must Go" in 2003.

In 2006, Fagen released his third solo album Morph the Cat, which is partly based on old age and death, and was well received by fans.