The Exorcist III is a 1990 American supernatural thriller written and directed by William Peter Blatty. It is the second sequel of The Exorcist series and a film adaptation of Blatty's novel, Legion (1983). The film stars George C. Scott, Brad Dourif, Ed Flanders, and Nicol Williamson. This is the only Exorcist film not to be distributed theatrically by Warner Bros.

Set fifteen years after the original film and ignoring the events of Exorcist II: The Heretic (1977), the film centers around the philosophical Lieutenant William F. Kinderman from the first film, investigating a baffling series of murders in Georgetown that appear to have a satanic motive behind them and furthermore have all the hallmarks of "The Gemini", a deceased serial killer.

Originally titled Legion, the film was drastically changed in post-production with re-writes and re-shoots ordered by the studio executives of Morgan Creek Productions, demanding the last-minute addition of an exorcism sequence, and the film was released as The Exorcist III in order to be more commercial. The final version differed from Blatty's vision; all of the cut footage is apparently lost.

Surprisingly good second sequel, especially given the quality of Exorcist II. Blatty is a pretty good director, as some of the shots are stunning in their patience and composition (the hallway scene especially). The visuals are impressive and effective, and not overused. Unfortunately, the story doesn't quite measure up. It's an interesting blend of the first Exorcist and the real-life Zodiac killings, but it doesn't work as well as it should, and sometimes loses the viewer to confusion. The ending doesn't fit at all, either, along with the whole subplot with Father Morning, though I know that's not Blatty's fault. Still, it takes away from the film, which doesn't need an exorcism at the end to remain effectively scary. All in all, it's a good film that unfortunately suffers from studio pressure.