General · EdgepediaOctober 3, 20266 min read

Monsters Inside: The 24 Faces of Billy Milligan

Monsters Inside: The 24 Faces of Billy Milligan is a 2021 American true-crime documentary limited series directed by Olivier Megaton and released on Netflix, examining the case of Billy Milligan, the Ohio man who was found not guilty by reason of insanity in 1978 after psychiatrists diagnosed him with multiple personality disorder, now called dissociative identity disorder, and counted as many as 24 distinct personalities within him¹. The four-part series interviews Milligan's family, friends, treating doctors, and the prosecutors and police who worked the case, and asks whether the personalities were real or a fabrication that let a violent offender avoid prison¹.

Key fact	Detail
Format	Four-part documentary limited series, Netflix; episodes 59 to 63 minutes each²
Release	Premiered September 22, 2021, with all four episodes released the same day³
Director	Olivier Megaton, whose feature credits include Taken 2 and Columbiana¹^•⁴
Production	Upside Films, distributed by Netflix; music by Lionel Limiñana and David Menke⁵
Central case	1977 rapes near Ohio State University; December 4, 1978 verdict of not guilty by reason of insanity, the first of its kind for dissociative identity disorder¹^•⁶
Reception	IMDb 6.3/10 from about 5,500 users; Rotten Tomatoes Tomatometer 33% from 4 critics⁷^•⁸

Spoilers

The case the series examines

In October 1977, police arrested 22-year-old William "Billy" Stanley Milligan for the kidnapping, robbery, and rape of women around the Ohio State University campus. The sources differ on the count: TIME reports three women⁶, while MovieMaker, quoting director Olivier Megaton, states that Milligan raped four women in ten days⁴. Upon arrest, Milligan said he had no memory of the assaults, and observers noted his mannerisms seemed to change on the spot¹.

During psychiatric evaluation, Milligan attributed the robberies to a personality named Ragen, described in press coverage as a Yugoslavian criminal, and the rapes to Adalana, a 19-year-old lesbian persona he said was desperate for love; Billy himself, he claimed, remained "asleep" while the alters acted⁶^•⁹. Doctors determined that Ragen and Adalana were two of ten alternate personalities formed, in their view, in response to severe physical and sexual abuse Milligan allegedly suffered at the hands of his stepfather, Chalmer Milligan; fourteen more identities were diagnosed later, bringing the total to 24⁶. Chalmer Milligan, who died in 1988, denied ever abusing the children, though childhood friends interviewed in the series said they witnessed the abuse⁴.

On December 4, 1978, Milligan was found not guilty by reason of insanity on charges including rape, kidnapping, and aggravated assault. The verdict was the first of its kind for a defendant claiming multiple personality disorder, and it remains controversial⁶^•¹⁰. After the verdict, Milligan spent roughly a decade in state-run psychiatric hospitals undergoing treatment intended to fuse his personalities into one⁴^•⁶.

Structure and content

The series opens with the crimes rather than the childhood. Megaton told MovieMaker that he began with the rapes so the audience would keep the victims in mind from the start, and he said the production located contact information for only two of Milligan's victims, neither of whom agreed to be interviewed⁴.

The four episodes, all released on September 22, 2021, are³^•²:

The Campus Rapist (59 minutes): the 1977 accusations near Ohio State University and the experts' questions about multiple personality disorder.
The Monsters Inside Me (59 minutes): Milligan's troubled youth through interviews with his siblings and childhood friends, and the unusual defense mounted at trial.
The Golden Age (61 minutes): Milligan's rise to celebrity, a new doctor who disagreed with the diagnosis and changed his treatment, and Milligan taking his care into his own hands.
The Escape (63 minutes): Milligan going on the run with help from friends and family, changing his identity, and mixing with Hollywood figures.

Interviewees include Milligan's sister Kathy Preston and brother Jim Morrison, the psychiatrists George Harding and Sheila Porter, prosecutors Ron O'Brien and Terry Sherman, attorney Lewis Williams, and Columbus Dispatch journalist Bob Ruth¹¹. Milligan, who died of cancer in 2014 at age 59 in Columbus, Ohio, appears through extensive archival interview footage⁴^•⁶.

Reception

Critical response was mixed, with the series' length the most common complaint. The Rotten Tomatoes Tomatometer stood at 33% from four reviews⁸. John Anderson of The Wall Street Journal wrote that the series had "too much space and not enough substance to fill it"⁸. Graeme Tuckett of The Post NZ called it "a fascinating, horribly compelling story, stretched in typical Netflix fashion, over four hours"⁸. Karina Adelgaard of Heaven of Horror judged that the story "should have been told in two strong episodes rather than four weak ones"⁵. On IMDb the series holds a 6.3/10 weighted rating from about 5,500 users, with individual episodes scoring between 6.4 and 6.7⁷.

Reviewers also questioned the series' balance. A Rotten Tomatoes audience review criticized the stylized interview setups and noted that the statements of interviewees, including author Daniel Keyes's claim that one of Milligan's alters could "speak fluent Serbo-Croatian", are never challenged⁸. Megaton himself told Salon that he was skeptical of Milligan's story from the beginning and that his aim was to understand how the story unfolded in the 1970s and 1980s rather than to decide whether to believe it¹².

Context and legacy

The Milligan case had already been chronicled in Daniel Keyes's 1981 non-fiction novel The Minds of Billy Milligan, written while Keyes participated in Milligan's therapy, and the Boston Globe noted that this dual role would now be considered a breach of journalistic and medical standards⁹. At one point James Cameron considered a feature film about Milligan, but the project fell through⁴.

The 2021 docuseries renewed public attention to the case: Apple TV+'s 2023 scripted limited series The Crowded Room, created by Akiva Goldsman and starring Tom Holland, is loosely inspired by Keyes's book, and TIME's coverage of that series pointed readers back to Monsters Inside as the documentary treatment of the same story⁶. The Los Angeles Times included Monsters Inside in its 2023 list of 50 notable true-crime documentaries on the major streaming services¹³.

The series also sits within a broader professional debate about dissociative identity disorder. Legal scholarship treats the 1978 Milligan verdict as the point at which multiple personality disorder was first recognized as a mental illness excusing criminal responsibility¹⁰, while psychiatric literature records continuing dispute over the diagnosis's validity and its forensic use¹⁴. The Netflix synopsis frames the series' central question accordingly: whether Milligan's personalities controlled his actions or served as cover for a manipulative offender¹.

References

Initially written Oct 3, 2026 · Reviewed: Oct 25, 2026 · Edited: Oct 15, 2026; Oct 21, 2026; Oct 25, 2026; Nov 1, 2026