Tammy Lynn Leppert was an American beauty queen and model. She had a few acting roles in the early 1980s but mysteriously disappeared at the age of 18. Her disappearance has generated much publicity, and her case remains open.

Leppert had aspirations for an acting career, though she lacked formal training in acting. In 1980, she had a bit part in the teen-oriented comedy-drama film "Little Darlings". The film's plot revolved around two teenage girls who placed a bet on which of them would lose her virginity first, while several other girls took an interest in their contest. In 1983, Leppert appeared as a female participant in a boxing match featured in the sex comedy "Spring Break". After the end of the film's shooting, Leppert decided to party. She went unaccompanied to a weekend party but reportedly had a disturbing experience there. After she returned home, Leppert started displaying signs of paranoia and persecutory beliefs. She was convinced that somebody would try to kill her and started taking precautions to prevent anyone from placing poison in her food and drink. Leppert's last acting role was in a key scene of the crime drama film "Scarface". Her role was that of a bikini-clad girl who intentionally distracts the lookout car, preventing its occupants from intervening in a torture scene. Leppert reportedly displayed irrational behavior on the film's set and was escorted to her home after the fourth day of filming.

On July 6, 1983, Leppert arranged for a male friend to drive her to an unspecified location. They argued during the drive, and the friend dropped her off at Cocoa Beach, Florida, not far from Leppert's residence. He was the last person to see her alive. Leppert vanished without a trace, and the police and FBI soon started investigating her disappearance. As of the early 2020s, the investigative authorities have acquired a DNA profile of Leppert, but they do not have her dental records and fingerprints. The FBI has theorized that Leppert was killed by serial killer Christopher Wilder (1945-1984), an amateur photographer who habitually targeted models and beauty contestants to rape and kill. Wilder lived in Florida from 1969 to 1984, and he went on a cross-country crime spree a few months following Leppert's disappearance. However, there is no physical evidence tying him to the case. Another major suspect was John Brennan Crutchley (1946-2002), a convicted rapist and kidnapper who was also suspected of being both a serial killer and a professional spy. Crutchley moved to Florida in 1983 and resided in the same county as Leppert. However, authorities were never able to prove that Crutchley had ever killed anyone.

Leppert's disappearance has ensured enduring fame from her, and she is often featured in true-crime books and documentaries. Various investigative authorities have repeatedly announced possible new leads when unidentified female corpses with superficial similarities to Leppert have been discovered. Between 1984 and 2014, the remains of 13 different women were compared to physical samples from Leppert, but none of them was an exact match. It is not clear whether Leppert is still alive or long gone.