Movie fans never know just how much time, money and energy is spent creating the next Hollywood hit before cameras ever start rolling. But as polished or acclaimed as a script may be, there’s no predicting what will happen when the cast and crew arrive on set. And sometimes, lines or scenes improvised on the spot can not only work, but become instant classics.

Here is our list of 10 Amazing Improvised Movie Moments.

Harry Potter and the Chamber of Secrets

Improvised Movie Lines Harry Potter

Entrusted to play beloved characters in 8 movies over the span of a decade, the cast of the Harry Potter series faced pressures few actors will ever experience. But even at a young age, they proved a talented group. When Lucius Malfoy arrived at the end of the second movie to claim his innocence, there was no line in the script to end the conversation. Actor Jason Isaacs asked for advice, and the director told him to simply make something up. Turning to the boy wizard and sarcastically hoping he would keep saving the day, the 12 year old Daniel Radcliffe didn't disappoint, reacting to Isaacs' veiled threat with a promise of his own. It was all the veteran actor needed to see to know Radcliffe was the real deal.

Fast & Furious 6

Improvised Movie Scenes Fast Furious Ludacris Tyrese

The Fast & Furious movie series owes as much of its success to the memorable cast as the high speed action. The love/hate relationship between Tej and Roman (played by "Luda"cris Bridges and Tyrese Gibson) is one fans favorite dynamic, with the latter's forehead a regular target for teasing. Roman can give as good as he gets, taking a playful shot at Dwayne 'The Rock' Johnson at the end of the sixth movie. Tyrese's baby oil line was scripted, but The Rock's reply wasn't, meaning both of his costars’ reactions were caught in real time.

The Departed

Improvised Movie Scenes Departed

Martin Scorsese's story of an undercover cop being pulled into a Boston crime family was overflowing with talented actors, with Jack Nicholson and Leonardo DiCaprio sharing a handful of incredible scenes. When Nicholson's mob boss suspects he has a rat in his crew, the young recruit talks tough to throw off suspicion. But Nicholson decided to add something to the scene without informing his costar. Pulling a gun out from under the table changed the tone of the scene entirely, visibly rattling DiCaprio. Staying in character, the actor used the added emotion to deliver an even better version that wound up in the finished film.

The Fellowship of the Ring

Improvised Movie Moments Fellowship Rings Knife

The Lord of the Rings ended with a massive war, but in the trilogy's first film, a fight between Strider and an Uruk-hai leader was thrilling enough - but it was more dangerous than audiences realized. During the fight, the orc actor was supposed to throw a stunt knife past actor Viggo Mortensen, who would dodge out of the way. But when the scene was filmed, the knife slipped, flying directly at Mortensen's face. The actor’s weapons training took over, instantly reacting by knocking the blade out of the air with his own sword. Fragments of the broken blade can be seen upon impact, since the mistake was too good to leave out of the final cut.

Die Hard

Improvised Movie Moments Die Hard Gruber Drop

Director John McTiernan and Bruce Willis relied on practical effects and a single skyscraper to make Die Hard one of the greatest action movies ever made. No fan will forget the death of the villain, Hans Gruber, who realized his plan was blown only as he dropped thirty stories off the building's edge. The effects have stood the test of time, but it's actor Alan Rickman's expression that sold the moment. But it wasn't truly acting: when Rickman was suspended for the real green screen drop, the director dropped him prematurely to guarantee the surprised look would be genuine. The actor wasn't impressed, but you can't argue with the results.

Thor

Improvised Movie Moments Thor Odin Loki Growl

Marvel's first movie starring the Asgardian god of thunder showed a lighter side to superheroics, but when Thor and Loki shared scenes with their father Odin, the result was downright Shakespearean. That was due largely to Tom Hiddleston and Anthony Hopkins, with emotions boiling over in one memorable moment. When Odin decides to banish Thor from his home, Loki comes to his defence, but is silenced by a menacing growl from his typically composed father. Apparently, the reply wasn't scripted. Hopkins simply snarled in character, and Hiddleston's stunned reaction - also in character - is just as improvised.

The Hobbit

Improvised Movie Scenes Hobbit Egg Throw

The story of Bilbo Baggins' greatest adventure begins as any Hobbit tale should: with a party. The dwarves who storm Bilbo's kitchen clearly know how to have fun, but not all their stunts and tricks are fuelled by CG. While shooting the scene, the cast decided to throw a hardboiled egg the length of the dinner table into actor Stephen Hunter’s mouth. What audiences see in the finished film is the very first take, with the actors just as thrilled and surprised to see it pulled off so perfectly.

Star Trek

Improvised Movie Lines Star Trek Bones

The original Star Trek TV series made James Kirk, Spock, Leonard McCoy and the crew of the USS Enterprise household names - which meant millions of fans who were less than happy to see the roles recast for the 2009 movie reboot. Karl Urban landed the role of Dr. McCoy, but older viewers knew the character better by his nickname: "Bones." The name was a play on the term sawbones, but Urban decided to add his own spin. The new McCoy still split with his wife before joining forces with Jim Kirk, but when it came time to shoot their introduction, Urban improvised a new explanation for his future nickname. Obviously, Abrams was a fan.

The Two Towers

Improvised Movie Scenes Lord Rings Two Towers

Directors don't insist on repeating takes just to make sure they have a wealth of choices in editing - sometimes, it's to help their actors warm up and execute a scene with added emotion. In the middle chapter of Peter Jackson's Lord of the Rings trilogy, Aragorn arrives to find what he believes are the burned remains of his Hobbit friends, kicking an orc helmet in anger and defeat. With each take, actor Viggo Mortensen knocked the helmet closer and closer to the camera, so Jackson kept resetting, until Mortensen let out a gut wrenching scream before falling to his knees. Jackson was impressed, but would find out the added emotion was due to the broken toes the actor suffered on the final take - the same one included in the finished movie.

Fight Club

Unscripted Movie Scenes Fight Club Punch

Once Tyler Durden steps out from the mind of Fight Club's narrator and into his life, he forces the high-strung zombie to express himself in an unusual way ("I want you to hit me as hard as you can"). When it came to shoot the scene, director David Fincher felt something more was needed, telling actor Ed Norton not to punch Brad Pitt in the shoulder, as they had planned, but to go for his ear, without giving him any warning. The decision paid off, with Pitt's reaction making it into the final movie as a fan favorite moment.

Conclusion

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