Mandy is a 2018 surrealist action horror film directed by Panos Cosmatos, from a screenplay he co-wrote with Aaron Stewart-Ahn, and based on a story by Cosmatos. A co-production between Belgium and the United States, it stars Nicolas Cage, Andrea Riseborough, Linus Roache, Ned Dennehy, Olwen Fouéré, Richard Brake, and Bill Duke. The film follows Red Miller (Cage), a lumberjack seeking vengeance against cult leader Jeremiah Sand (Roache), as well as his devout followers, for the murder of his girlfriend, Mandy Bloom (Riseborough).

Mandy premiered at the Sundance Film Festival on January 19, 2018, and was theatrically released in the United States on September 14, 2018. The film was a box office failure, grossing $1.7 million against its $6 million production budget. Despite this, it received critical acclaim, with particular praise for its visual style and originality, Cage's performance, Cosmatos' direction, and the action sequences.

At the 45th Saturn Awards, the film won for Best Independent Film, while Cage was nominated for Best Actor. Benjamin Loeb was nominated for Best Cinematography at the 34th Independent Spirit Awards. Mandy was one of the last films to be scored by composer Jóhann Jóhannsson, who died of drug-related complications seven months before the film's release, and the film is dedicated to his memory.

In 1983, in the Pacific Northwest, recovering alcoholic war veteran lumberjack Red Miller lives with his girlfriend, artist and author Mandy Bloom, who had an abusive childhood. Mandy works as a gas station cashier by day and at night creates elaborate fantasy art, which Red greatly admires.

While walking to work, Mandy catches the attention of Jeremiah Sand, leader of the religious cult Children of the New Dawn. Sand orders his disciple Brother Swan to kidnap Mandy. Swan summons the Black Skulls, a cannibalistic, demonic biker gang that regularly consumes LSD.

After being offered a cult member as a sacrifice, the gang breaks into their home and subdues Mandy and Red. Cultists Mother Marlene and Sister Lucy drug Mandy before presenting her to Sand. The cult leader attempts to seduce Mandy with his psychedelic folk music, but she just laughs at Sand, infuriating him. In retaliation, Sand stabs the bound and gagged Red and burns Mandy alive before him. After Sand and his followers leave, Red frees himself, mourns Mandy's death, and, after consuming a bottle of vodka, wordlessly swears revenge.

The next morning, Red visits his friend Caruthers to retrieve his crossbow and bolts. Before Red leaves, Caruthers warns him of the Black Skulls; Red reinforces his determination by forging a battle axe. He shoots a biker with his crossbow and runs him down, but the biker crashes his car and Red is captured in the process. At their hideout, Red breaks free from his restraints and kills the rest of the bikers. As he investigates their hideout, he ingests some of their drugs, causing him to instantly and severely hallucinate.

Following the images in his visions, Red finds The Chemist, the person who made the Black Skulls' LSD. The Chemist tells Red where to find the cult. At their makeshift wooden church in a quarry, Red kills the cult members one by one in increasingly brutal fashion. In the tunnels beneath the church, Red finds Mother Marlene and decapitates her. He then confronts Sand, taunting him by throwing Marlene's severed head at him before crushing his skull. He sets Sand's body and the church on fire before driving away. As Red drives, he hallucinates Mandy smiling in the passenger seat of his car, while the landscape behind him now appears fantastical and otherworldly.