Murphy's theatrical debut, Gorillas in the Mist, was nominated for an Academy Award for his writing.

Afterwards, Murphy has spent nearly ten years with The Walt Disney Company writing The Hunchback of Notre Dame in 1996, Tarzan in 1999, Atlantis: The Lost Empire in 2001, and Brother Bear in 2003.

During his time with Disney, he was hired by TriStar Pictures to write a treatment to a planned sequel to the 1998 film Godzilla.

His work includes Superman/Batman: Apocalypse and Batman: Year One, and he wrote several episodes for the 2011 Thundercats reboot, Teen Titans Go!

He was attached to write an animated feature directed by Kirk Wise called Galaxy Gas,[3] and a TV pilot that was sold to Legendary Pictures.