Lethal Weapon is an American buddy cop action-comedy media franchise created by Shane Black. It focuses on two Los Angeles Police Department (LAPD) detectives, Martin Riggs and Roger Murtaugh. The franchise originally consisted of a series of four films released between 1987 and 1998, and later a television series which aired from 2016 to 2019. The first four films in the series were directed by Richard Donner and also share many of the same core cast members, while the television series recast the main roles with younger actors instead. Though the first film was not explicitly a comedy, the later films and the television series gradually became comedic in nature.

A proposed fifth Lethal Weapon film had been in talks and development since 2007, but has yet to make it into production.

Lethal Weapon (1987)

Anxious with age and retirement, homicide detective Roger Murtaugh (Danny Glover) is partnered with young and suicidal narcotics officer Martin Riggs (Mel Gibson). Together, they work the case of the alleged suicide of Amanda Hunsaker (Jackie Swanson), daughter of a wealthy businessman who served with Murtaugh in Vietnam. Murtaugh and Riggs soon discover that Hunsaker was involved in a heroin-smuggling scheme led by a retired general (Mitchell Ryan) and his lead enforcer (Gary Busey).

Lethal Weapon 2 (1989)

During a car chase, Riggs and Murtaugh stumble upon a trunk full of smuggled South African Krugerrands. This sparks a series of attempts at their lives, forcing them to take a less dangerous case, protecting Leo Getz (Joe Pesci), a loud-mouthed whistleblower with whom they gradually bond and befriend. However, they realize that Getz was involved in the same South African illegal activities. As a result, the three men become entangled in a drug-smuggling operation involving South African diplomats in Los Angeles, using their immunity and biting wit as a shield. Riggs kills the murderer of his wife who is among the criminals.

Lethal Weapon 3 (1992)

As Murtaugh, who is one week from retiring, and Riggs investigate a robbery committed using a duplicate armored car, they find themselves in the middle of an Internal Affairs investigation led by Sergeant Lorna Cole (Rene Russo). With assistance from Leo, they learn that the subject of the investigation is a rogue AWOL cop (Stuart Wilson) who is stealing impounded weapons and selling them on the black market. During the investigation, Murtaugh shoots and kills a teenager who attacks him and Riggs; he turns out to be a friend of his own son. This prompts Murtaugh to capture the man responsible for the distribution of illegal firearms and to rethink his retirement.

Lethal Weapon 4 (1998)

While Lorna and Murtaugh's daughter Rianne are both pregnant, Riggs and Murtaugh once again team up with Leo as well as rookie Detective Lee Butters (Chris Rock) to investigate a Chinese immigrant smuggling ring. Wah Sing Ku (Jet Li) is a ruthless enforcer who personally attempts to murder Murtaugh's family by burning them alive in their own home. As the story progresses, Murtaugh discovers that Lee is the father of his daughter's unborn child. The two slay dozens of Chinese gangsters and ultimately manage to catch up with the boss of the smuggling ring. Riggs and Lorna are married at the end of the film as their child is born.