Featuring serial killers, brutal maulings, and unsolved mysteries, documentaries can be far creepier than anything George Romero has ever imagined—because they depict things that really happened. These 10 films are impossibly disturbing, based on true events, and guaranteed to stick with you long after the end credits have rolled.

1. GRIZZLY MAN (2005)

Grizzly Man is a nature documentary like none you’ve ever seen: Struggling actor and alcoholic Timothy Treadwell was always an eccentric who felt more comfortable among animals than he did people. One summer, Treadwell sold everything and moved up to Alaska to live in the wilderness among the grizzly bears, filming them and closely interacting with them. Directed by Werner Herzog, Grizzly Man takes Treadwell’s astonishing footage and pieces together his life during the 13 summers that Treadwell spent in exile. Until Treadwell and his girlfriend, Amie Huguenard, were attacked and killed by one of the animals he loved, while one of Treadwell’s cameras caught the audio of the attack.

Why it’s so creepy: Herzog chooses not to include the audio of Treadwell’s death in the final film, but the attack and what’s on the tape is discussed in graphic (and unsettling) detail. EHerzog surmises that the bear who ultimately killed Treadwell was likely one of the animals that he filmed, and loved. This puts the viewer in an uncomfortable position: Watching Treadwell film and play alongside the bears, knowing that he’s likely engaging with his future killer.

2. THERE’S SOMETHING WRONG WITH AUNT DIANE (2011)

From the movie’s offset, we know that something terrible has happened. The documentary opens with several harried calls to 911, describing a horrific crash off the Taconic State Parkway. The crash, which occurred in 2009, would later become known as the worst Westchester County traffic fatality in 30 years, killing eight people including the driver, Diane Schuler, her two-year-old daughter, and her three young nieces. The film documents the Schuler family and their quest to piece together Diane’s final moments: Why did Schuler, a responsible and devoted mom on her way home from a family camping trip, drive the wrong way down the Taconic Parkway?

Why it’s so creepy: There’s Something Wrong With Aunt Diane profiles a woman who seems to have everything under control. At the time of her death, Schuler had two adorable kids, a happy marriage, and a successful career with a six-figure income. So when the film reveals why Schuler drove nearly two miles down the Taconic Parkway in the wrong direction with five young children in tow, the reason is almost too terrible to believe. Aunt Diane compels viewers and, at the same time, mystifies us with the eternal question: How well can you really know another person?

3. BOY INTERRUPTED (2009)

When filmmaker Dana Perry’s son Evan turned five years old, she noticed that he had a strange preoccupation with death and dying. Perry immediately took Evan to a therapist, and she and her filmmaker husband Hart flipped on the camera to record his increasingly bizarre behavior. As Evan grows, the Perrys document Evan’s tumultuous struggle with depression and bipolar disorder, culminating in his suicide in 2005 at the age of 15. Boy Interrupted becomes the Perry’s loving tribute to a son who both mystified and terrified them.

Why it’s so creepy: Boy Interrupted shows that mental illness and suicide doesn’t discriminate. Filmmakers Hart and Dana Perry are obviously attentive, caring parents, and many times they literally uproot their lives to support Evan through his struggle. But bipolar disorder has a suicide rate of nearly 17 percent—and that’s an uncomfortable fact that the Perrys put in the forefront of their film. Watching their story unfold, and knowing that nothing can stop the slow decline into Evan’s suicide, will send shivers down your spine.

4. THE JINX (2015)

HBO’s The Jinx tells the story of Robert Durst, heir to one of the oldest real estate companies in New York City and the prime suspect in series of bizarre crimes, including the disappearance of his wife, Kathleen, in 1982. The Jinx is a documentary miniseries, one that takes six episodes to detail every bizarre crime in which Durst is involved. After his wife’s disappearance, Durst’s close friend Susan Berman is found murdered in 2000 when Kathleen’s case is reopened. Durst maintains his innocence in both crimes and flees to Galveston, Texas. But when police catch up to him one year later, Durst has been implicated in yet another murder (Durst is charged and pleads self-defense, by the way). Director Andrew Jarecki (who directed 2010’s All Good Things, a feature based on Durst) examines Durst’s alleged crimes, documents the trial for his most recent murder, and speculates whether Durst is actually guilty of all three crimes—or just one of the unluckiest men on the planet.

Why it’s so creepy: Bob Durst is like that weird uncle you only see at Christmas: He’s quiet, mild-mannered, and even a little likeable at times. Watching him recount his friends’ deaths, completely emotionless, is chilling. And knowing that he likely could have killed several people in cold blood? Unsettling. (Also unsettling? His beady, black eyes.)

5. BLACKFISH (2013)

Have you ever seen those SeaWorld commercials where the dolphin trainers are talking about how much they love whales? Blackfish is the reason those commercials exist in the first place. It’s a riveting documentary that covers the story of Tilikum, a captive killer whale that mauled a SeaWorld trainer in 2010. What begins as an expose of Tilikum (who apparently has killed before) gradually turns into an indictment of SeaWorld as a whole.

Why it’s so creepy: If you have any childhood memories of SeaWorld, prepare to have them forever ruined. The whales appear happy when performing in front of a crowd—but according to Blackfish, that’s almost certainly a ruse. Seeing footage of Tilikum playing around with trainer Dawn Brancheau before her death, and knowing what will eventually happen between them, is eerie.

6. DEAR ZACHARY (2008)

Don’t Google this film. It’s best to go into Dear Zachary knowing as little about what happens as possible.

Without giving too much away, the gist is this: Dear Zachary is director Kurt Kuenne’s attempt to immortalize his best friend Andrew Bagby, a physician killed in cold blood by his estranged girlfriend, Shirley Turner. Kuenne seeks out friends and family to sing their praises of his late friend—and then the film takes a shocking turn. Turner, Bagby’s killer, announces while in police custody that she’s four months pregnant with Bagby’s child. And Kuenne’s film becomes something entirely different: A critique of the Newfoundland legal system, an exposé of the custody case between Turner and Bagby’s parents, and a letter to Zachary, Bagby’s son, about the man his father once was.

Why it’s so creepy: Not only is the viewer subjected to graphic details about Bagby’s murder, Kuenne also uses archival footage of Turner and Bagby during their brief relationship. Watching Turner interact on camera with Bagby, hearing about what she did in the hours after Bagby’s death, and seeing footage of her eventually mothering Bagby’s child will leave you with chills whenever she’s onscreen.

7. THE BRIDGE (2006)

San Francisco’s Golden Gate Bridge is one of the world's most popular tourist sites—and according to this film, it’s the most popular spot to commit suicide. Over the course of one year, filmmaker Eric Steel and his crew spent hundreds of hours filming footage of the Golden Gate Bridge, and managed to capture the deaths of nearly two dozen jumpers. Steel then interviews the families of some of the individuals and sets out to discover what draws so many people to the Golden Gate Bridge—and what compels some to end their lives there.

Why it’s so creepy: Several suicides are caught on film. Enough said.

8. PARADISE LOST (1996)

In 1993, the bodies of three mutilated children were discovered in a wooded area of West Memphis, Arkansas. Quickly, after one teen admits to being an accomplice, a trio of teenagers is arrested in connection with the crime, tried in a court of law, and found guilty. An open-and-shut case, right? Wrong. The film, which follows the families of the victims and the accused throughout the trial and its aftermath, is equal parts true crime documentary and an indictment of a small-town criminal justice system. Was the teenager’s confession coerced? Were the murderers ever really caught?

Why it’s so creepy: If the opening footage of three mutilated kids isn’t creepy enough for you, the entire movie is replete with graphic retellings of the crime. But the more frightening part of watching the film is the growing realization that the three teenagers accused of the crime—Damien Echols, Jessie Misskelley, and Jason Baldwin—might possibly be innocent. The Emmy-winning documentary was followed up two sequels, in 2000 and 2011—with the final film detailing the West Memphis Three's release from prison.

9. THE IMPOSTER (2012)

When 13-year-old Nicholas Barclay goes missing in 1994, his family gradually accepts that he may not be coming home. But three years later, in 1997, Barclay’s family gets a phone call that Nicholas has been found—alone and terrified—in Spain, thousands of miles from his Texas hometown. Stunned, his family joyfully welcomes him home. But it soon becomes clear that the boy who went missing three years prior is not the same person—literally—as the one who comes home.

Why it’s so creepy: Since the name of the documentary is The Imposter, it’s pretty obvious from the start that the person claiming to be Nicholas Barclay isn’t actually Nicholas Barclay. But what kind of person would impersonate a missing child? Director Bart Layton manages to snag one-on-one interviews with the man who pretended to be Barclay, and hearing him retell how he manipulated the Barclay family (often smiling and laughing good-naturedly while he recounts the story) will give you goosebumps.

10. ALBERT FISH: IN SIN HE FOUND SALVATION (2007)

Albert Fish was one of the country’s most depraved serial killers—and considering that serial killers are pretty depraved to begin with, that’s saying something. Fish suffered from extreme mental illness from an early age and began experimenting with extreme taboos as a young adult, eventually moving on to prostitution, child molestation, and murder. This documentary goes into graphic detail about the hundreds of murders Fish was linked to—and the hideous way he disposed of the bodies afterward.

Why it’s so creepy: Fish was extremely candid about his crimes, and kept detailed, first-person accounts of them which are read throughout the documentary. At one point, Fish actually details the murder of one young girl in a letter and then mails the letter to her mother. It’s almost impossible to listen to what Fish did—or see reenactments of Fish walking hand-in-hand with his victims—and not feel chills.