A.J. "Mitch" Mitchell provided the electronic effects for the Doctor Who television stories Underworld and The Stones of Blood. He later provided the video effects for Nightmare of Eden and Full Circle. He had earlier been an uncredited inlay operator on The Android Invasion. (INFO: The Android Invasion)
He also provided effects on the last part of Warriors of the Deep under the name John Mitchell.
He was the subject of a two-part interview in DWM 187-188, and was featured in the documentary Into the Unknown included on the DVD release of Underworld. Mitchell is the author of the 2004 book Visual Effects for Film and Television.