Martin Riggs, played by Mel Gibson

• Anti-Hero: Type II in every movie but the first.
• Ax Crazy: Primarily in the 1st movie, mellows down in the sequels. Hence he's also...
• The Berserker
• Byronic Hero: In the original.
• Badass
• Bunny-Ears Lawyer
• Cartwright Curse: Until the third movie. Although Lorna does get shot in the climax of Lethal Weapon 3, and for a while there it looks like she may not survive.
• Cowboy Cop
• Deadpan Snarker
• Death Seeker: In the first movie.
• '80s Hair: In every movie except the fourth.
• The Gadfly: Enjoys teasing ol' Rog to no end.
• Good Is Not Nice
• Hair-Trigger Temper: He actually pretends to have this in order to scare his enemies.
• Hot Blooded
• Improbable Aiming Skills: Justified. He was a Special Forces Sniper in Laos and Vietnam. He once made a hit that he thinks only ten other people in the world might have been able to make.
  Riggs: It's the only thing I was ever good at.
• Jerk with a Heart of Gold
• Large Ham: Especially in the first movie. He's become more composed in the sequels.
  "Do you really wanna jump?! DO YOU WANNA?!?"
• Lightning Bruiser
• Salt
• Sociopathic Hero: Just in the first movie.
• Title Drop: In the first movie, Roger refers to him as a "lethal weapon."

Roger Murtaugh, played by Danny Glover

• Badass Mustache
• By-the-Book Cop
• Catch Phrase: "I'm too old for this shit." Inverted in the fourth movie.
  • "Riggs you crazy sonuva b...." as well
  • "Go spit, Riggs!"
• Character Tic: He cracks his neck before shooting people.
  • This is typically followed by a Boom, Headshot.
• Deuteragonist
• Heroic BSOD: After killing an old friend of his son's out of self-defence, leading on to...
  • Drowning My Sorrows
• Overprotective Dad
• Papa Wolf
• Pepper
• Sanity Chain
• Retirony: Subverted in the 3rd movie.
• Revolvers Are Just Better: Though, he does carry an automatic as a backup weapon.
• Younger than They Look: Danny Glover was only 40 years old when he filmed the first movie despite supposedly being "too old for this shit". Murtaugh was written as an older character (50 in the first movie).

Leo Getz, played by Joe Pesci

• Butt Monkey
• Catch Phrase: "They fuck you with/at..."
• Chew Toy
• Cluster F-Bomb
• Jerk with a Heart of Gold
• Motor Mouth
• Nice Hat: In the fourth movie.
• Plucky Comic Relief

Lorna Cole, played by Renee Russo

• Action Girl
• Cowboy Cop
• Distaff Counterpart: To Riggs.
• Pregnant Badass: Kicks the asses of Wah Sing Ku's goons in the 4th movie.
• Tsundere

Lee Butters

• Genius Bruiser: He has a psychology degree.
• Hot Blooded
• Large Ham
• Meaningful Name: He constantly tries to "butter" his father-in-law up.
• Mistaken for Gay: Thanks to Riggs, poor Roger believes Lee swings that way.
• My Name Is Not Durwood: Riggs and Murtaugh have major difficulty in getting his name right.
• Uncle Tomfoolery: A not too offensive version.
• Wretched Hive: Where he had grown up in, and the reason he joined the police force.

General McAllister

• Big Bad: In the 1st movie
• General Ripper: He used to be this.

Mr. Joshua

• Backstab Backfire: Trying to shoot someone in the back when you are surrounded by cops is not a smart idea.
• Blond Guys are Evil
• The Dragon
  • Dragon Their Feet.
• Establishing Character Moment: Allowing the general to burn his arm, while Joshua clenches his teeth and takes it, establishing Joshua's loyalty (and insanity).
• Evil Albino
• Evil Counterpart: To Riggs in the 1st movie.
• Fisticuffs Boss
• Psycho for Hire

Arjen "Aryan" Rudd

• Big Bad
• Diplomatic Impunity: And he's not even a consul or ambassador.
• Politically Incorrect Villain
• You Have Failed Me

Pieter Vorstedt

• Backstab Backfire
• The Dragon
• You Killed My Father: He's responsible for the death of Riggs's wife.

Jack Travis

• Big Bad
• Evil Brit: Well, played by a British actor, anyway. The character is American.
• Dirty Ex-Cop
• Hoist by His Own Petard: Killed by the same "Cop-killer" bullets he has stolen and smuggled.

Wah Sing Ku, played by Jet Li

• Arrogant Kung-Fu Guy
• Badass: Probably the most Badass character in the entire series.
• Catchphrase: "In Hong Kong, you'd be dead".
• Dragon Ascendant: He killed his boss, which he threatened to early in the film.
• Dragon-in-Chief/Big Bad
• Even Evil Has Loved Ones
• Implacable Man
• Lightning Bruiser
• The Triads and the Tongs: One of these guys.