Every great film begins with a script, which must be adapted into live-action by a competent director - entrusting the right cast to do the story justice. But it's nearly impossible for a modern film to hit the big screen without some changes along the way. Oftentimes, that means tweaking or outright shedding scenes that steal attention away from the movie's larger moments and plots. But occasionally, it's the moments when actors go OFF the script that is most remembered.

To offer just a small taste of the evidence, we present you with our list of the 10 Greatest Unscripted Movie Scenes.

Raiders of the Lost Ark (1981)

Best Unscripted Movie Scenes Raiders Lost Ark

When Indiana Jones' leading lady is kidnapped in search of a holy relic in Raiders of the Lost Ark, the film's hero finds himself seriously outmatched. Instead of trying to actually fight a skilled swordsman, Jones simply pulls out his gun and drops his opponent with a single shot. The original script had called for a lengthy fight sequence, but when Harrison Ford was struck with food poisoning the night before filming, his energy was so sapped on set, he asked Steven Spielberg if he could simply shoot the man instead. The director agreed, and one of Indy's most iconic moments was born.

The Dark Knight (2008)

Best Unscripted Movie Scenes Dark Knight Joker Clap

Heath Ledger's Joker is a comic book villain for the ages, blending anarchy with dark humor in nearly every one of his scenes in Christopher Nolan's The Dark Knight. After finding himself in police custody, he witnesses firsthand Jim Gordon's promotion to the rank of Police Commissioner. As the officers in the room applaud their colleague, the mocking, expressionless clapping from the jail cell grabs all their attention, putting the camera squarely on Joker - a chilling moment that Ledger completely improvised during the scene.

Taxi Driver (1976)

Robert De Niro holding a gun in the mirror in Taxi Driver

Martin Scorsese and Robert DeNiro will forever be remembered for the chilling tale of Travis Bickle, the insomniac star of Taxi Driver - particularly Bickle's unforgettable mirror monologue centered on a single question: "You talkin' to me?" But the script only stated that Travis should begin speaking to himself in front of the mirror, without any specific details on what sort of scene to play out. The lines which followed were improvised by DeNiro entirely on the spot, with his words, raised eyebrow, and general attitude coming to define the actor for decades to come.

Aliens (1986)

Best Unscripted Movie Scenes Aliens Game Over Man

James Cameron's sequel to Alien helped define the sci-fi genre of futuristic space marines now seen in film, TV, and even video games - but not every one of those soldiers has what it takes to bring down the franchise's Xenomorph enemies. After the first attack decimates the marines and their drop ship crash lands, the script called for Private Hudson - played by Bill Paxton - to panic, but the actor decided to add a bit of video game lingo to the line, giving the film - and the genre - one of its most beloved quotes: "Game Over, man!"

The Usual Suspects (1995)

Best Unscripted Movie Scenes Usual Suspects Lineup

The most iconic scene from Bryan Singer's The Usual Suspects centers on a police line-up of the film's main cast of criminals. But writer Christopher McQuarrie came up with just a single line of dialogue for each actor to repeat, meaning it was up to the actors to shape the rest of the scene. When it came time to film, the actors sought to outdo one another, turning the scene into a mess of laughter. Even McQuarrie himself - playing the police officer on the intercom - got in on the action, asking actor Benicio del Toro to offer the line "in English please," getting an unscripted response in return.

Jaws (1975)

The shark and Martin Brody in Jaws

The underwater menace of Steven Spielberg's Jaws goes unseen for most of the film, finally revealing its incredible size as Police Chief Brody is throwing chum overboard to attract it, leaving him (and the audience) in shock. As Brody comes to his senses, he turns to the vessel's captain to inform him that "you're gonna need a bigger boat." The warning was improvised by actor RoyScheider during the scene, with the success of the film making it one of the most famous lines in movie history.

The Empire Strikes Back (1980)

Best Unscripted Movie Scenes Star Wars Empire

When the heroes of Star Wars find themselves ambushed during the final act of The Empire Strikes Back, Han Solo is captured by the bounty hunter Boba Fett, planned to be frozen in carbonite and returned to Jabba the Hutt. With his character's future uncertain, Han and Leia were meant to say their goodbyes in the form of matching "I love you"s. But director Irvin Kershner felt something was missing, and told actor Harrison Ford to simply respond the way he felt his character should before shouting "Action!"

What Ford came up with captured the smuggler's attitude perfectly, and offered a line no Star Wars fan will ever forget.

The Shining (1980)

Best Unscripted Movie Scenes Shining Heres Johnny

Stanley Kubrick's tale of supernatural and psyhological terror was an instant classic, due as much to Jack Nicholson's crazed descent into madness as the novel upon which The Shining was based. When Jack turns on his family - chasing his wife and son into a bathroom - he begins chopping through the door with a fire axe, before offering a twisted version of the phrase made famous on The Tonight Show with Johnny Carson: "Heeeeeeere's Johnny!" The line became a shorthand for the entire movie, despite it not appearing in Kubrick's original screenplay, improvised by Nicholson during the scene.

The Silence of the Lambs (1991)

Best Unscripted Movie Scenes Silence Lambs Hannibal

Few cinematic psychopaths have even come close to the character of Dr. Hannibal Lecter, played by Anthony Hopkins in The Silence of The Lambs. While Hopkins proved chilling in every one of his scenes, 'Hannibal the Cannibal' cemented his legacy with a single anecdote involving a dinner of "fava beans, and a nice chianti." Hannibal's specific tastes were found in the script, but Hopkins' unsettling suckling sound effect wasn't. The actor had started making the sound to creep out his co-star Jodie Foster during rehearsals, and the director decided it was too good to leave out.

Dumb & Dumber (1994)

Best Unscripted Movie Scenes Dumb and Dumber

Jim Carrey and Jeff Daniels came up with more than a few unforgettable exchanges and physical gags as the co-leads of Dumb & Dumber, but for a scene in which a hitman discovers how the pair entertain themselves on long road trips the duo went completely off script. The back and forth wordplay, poking, and Carrey's reveal of 'the most annoying sound in the world' were all thought up on the spot with no warning given to the actor between them - meaning his reaction was genuine.

Conclusion

Best Unscripted Movie Scenes List Video

So what do you think of our list? Did we miss any of your favorite improvised or unscripted scenes? Let us know in our comment section and don't forget to subscribe to our channel for more videos like this one.