Short answer: There are four Lethal Weapon films released between 1987 and 1998. Details

• Lethal Weapon (1987)

• Lethal Weapon 2 (1989)

• Lethal Weapon 3 (1992)

• Lethal Weapon 4 (1998)

Notes

• A fifth film has been discussed at various times, but no release has occurred, and the series effectively consists of four feature films plus a later TV series reboot. For context, different sources summarize the franchise as four films plus a television series, with mentions of past development talks for a fifth installment.