Evil Spawn

Ross Anderson

Evelyn Avery (as Donna Shock)

Harry (as Jerry Fox)

Monica Roarke

Brent

Elaine

Mark Randall

Tracy

Will

Betty

Dr. Leibowitz

Det. Samanski

Bordona

Pool Guy

Dr. Emil Zeitman

Erin West

Max Adrian

Dan Thorn

Samanski

Secretary

The only performer to be in "both" versions ("Evil Spawn" and "The Alien Within") is Forrest J Ackerman, who was hired by producer Fred Olen Ray to help tie the separate actions in the "revised version" together. Co-star Suzanne Ager came up with the title "The Alien Within"; working title was "Metamorph".

John Carradine's appearance as "Dr. Zeitman" was a "generic" scene shot by Fred Olen Ray with the intention of dropping it into subsequent films. The dialogue uttered by Carradine and actress Dawn Wildsmith (Ray's wife at the time) makes no specific references to the film's plot, allowing it to be easily re-used.

Producer Fred Olen Ray is the only constant throughout the history of the project. He directed and produced the ambiguous scene between John Carradine and Dawn Wildsmith (then Mrs. Ray), ostensibly for a Frankenstein film; he produced (but did not direct) the whole of "Evil Spawn," written to include pre-extant Carradine footage; and he produced the re-edited "remake," "Alien Within." The approximately 35 minutes of new footage was shot in and around his home in Hollywood.