The Astral Factor is a 1978 American horror film directed by John Florea, also known as Invisible Strangler or The Astral Fiend, starring Robert Foxworth, Stefanie Powers, Cesare Danova, Sue Lyon and Elke Sommer. Arthur C. Pierce wrote the screenplay and co-directed the film uncredited.

Plot
Studying the paranormal allows a convicted strangler to make himself invisible to kill five women who testified against him at his trial. The movie is about trying to catch the invisible murderer.

Cast
Robert Foxworth as Lt. Charles Barrett
Stefanie Powers as Candy Barrett
Sue Lyon as Darlene DeLong
Mark Slade as Detective Holt
Leslie Parrish as Colleen Hudson
Marianna Hill as Bambi Greer
Elke Sommer as Chris Hartman
Percy Rodrigues as Captain Wells
Alex Dreier as Dr. Ulmer
Rayford Barnes as Sgt. Archer
Frederick Tully as Detective Sloan
Frank Ashmore as Roger Sands
Larry Golden as Detective Rouseau
Renata Vaselle as Roxane Raymond
Cesare Danova as Mario
Eddie Firestone as Jacobs
Bill Overton as Kingsley
Carol Blalock as Sgt. Davis
Jennifer Burton as Policewoman
George Cheung as Jim, Medical Examiner
Albert Cole as Cop in Alley
John Hart as Harbormaster
Robert F. Hoy as Harris
Harry Lewis as Stage Manager
Walter O. Miles as Fingerprint Man
Queenie Smith as Darlene’s Landlady
Al Tipay as Miller
Frank DeSal as Prison guard
Troy Melton as Prison guard
George Robotham as Cemetery Guard
Jerry Wills as Cop
Budd Bryan as Lead Dancer
Bea Marie Busch as Dancer
Bonnie Evans as Dancer
Kathy Gale as Dancer
Marcia Hewitt as Dancer
Nancy Martin as Dancer
Judy Van Wormer as Dancer