As polished or hilarious as a movie script might be, it usually pays to let talented actors flex their muscles in front of the camera. Whether it’s on-the-spot jokes, or in-the-moment drama and action, the most memorable movie moments come when the script is tossed out the window. Here are Screen Rant’s 20 Greatest Unscripted Movie Moments.

The Avengers

As witty as writer/director Joss Whedon was when it came to the script of The Avengers, Robert Downey, Jr. did him one better. When the script called for Iron Man to call Thor “Shakespeare in the Park,” Downey got the idea, delivering one of the movie’s biggest laughs, right off the top of his head.

X-Men

Hugh Jackman may have been called in to play a live-action Wolverine at the last minute, but he made his mark on the cast immediately. While filming his first scenes in Xavier mansion, he decided to take an unscripted shot at Professor X They probably knew then that he already had Logan’s characters perfectly formed, – humor and all.

Amazing Spider-Man

There’s no limit to Emma Stone’s charm, which means that even when she accidentally calls her superhero boyfriend by his REAL name the cameras keep rolling. She was supposed to say Spider-Man, and her reaction was completely genuine, but perfect for the character.

Edge of Tomorrow

There isn’t much time for romance when aliens are slaughtering Tom Cruise day after day, but when his co-star Emily Blunt decided that forgetting her line, and just kissing him instead felt like the right move for the scene, he was left to react as best he could, with the cut used in the finished movie

Top Gun

It isn’t just Tom Cruise who GETS kissed without warning, either. The love scene from Top Gun became famous before it left theaters, but it started by accident. When Cruise and his co-star Kelly McGillis faced off on the street, he actually just forgot his line, and kissed her instead – the perfect way to get to love from hate.

Mr and Mrs Smith

Strange things happen when the same scene is shot over, and over, and over again. But when Angelina Jolie had the same Jeopardy clip drilled into her brain, she couldn’t help but blurt out the answer in between her lines. And that’s just the kind of random moment directors can’t help but include in the final cut.

The Matrix

Keanu Reeves put in the work to master martial arts for his role as The One, with Bruce Lee an obvious idol. So when the sparring session allowed he and Lawrence Fishburne to loosen up, Reeves couldn’t help but throw in Lee’s patented nose flick, even though it wasn’t in the script.

Pulp Fiction

When an actor like Samuel L. Jackson decides to improvise, other actors just try to keep up. After delivering his hamburger monologue in his first Pulp Fiction scene, Jackson decided to flip a table without warning the actor sitting at it. The move was brilliant, and audiences still get to see the stunned, completely honest reactions.

Fast & Furious

Brian O’Conner got a rough welcome to Dominic Toretto’s gang, first tangling with his friend Vince over Dom’s sister Mia. After some rough fight choreography didn’t go as expected, director Rob Cohen told the actors to just… well, fight. What you see in the film is a completely improvised street fight – and it shows.

Guardians of the Galaxy

The first fans saw of Marvel’s Guardians of the Galaxy was the criminals’ arrest and line-up, and the scenes summed up each character pretty well. It was Star-Lord’s finger cranking that got the biggest laugh, and was thought up by Pratt completely on the spot. Director James Gunn told him to add an apology, and the bit was complete.

Speed

It’s still hard to imagine Keanu Reeve’s jump from Bill and Ted to a certified action star in Speed, and director Jan de Bont knew that audiences might not realize the movie’s hero was as smart as he was. Needing to show that Officer Jack Traven was thinking through as problem, a pack of gum became the answer. Chewing means thinking after all – and it actually worked.

End of Watch

Nothing shows a vulnerable side to a character like singing in their car, and in End of Watch, audiences got to see Jake Gyllenhaal and Anna Kendrick’s characters make a duet of Camron’s “Hey Ma.” But it actually wasn’t their characters. Director David Ayer was in the backseat preparing to shoot written scenes for the pair, when they shared the song while getting to know eachother – with his camera rolling the whole time.

Titanic

James Cameron knew he had one-of-a-kind stars, and encouraged Kate Winslet and Leo DiCaprio to improvise a few times in the film. The best came when he told Winslet not to throw a hairpin at actor Billy Zane as planned, but spit right into his face. She did it, and Zane’s very real reaction can be seen in the film.

Ghostbusters

There were plenty of comedy legends to choose from in the first Ghostbusters, but it’s Rick Moranis who comes away as the most underrated. As the incredibly weird neighbor Louis, the rambling lines and monologue given while hosting a party in his apartment was almost completely improvised, moment by moment.

This is The End

The minds behind the movie claim that almost the entire shoot was improvised, and it shows. But the improv didn’t actually need much to get off the ground. The scene involving the gang getting into a heated argument over a single Milky Way bar is 100% unscripted.

Batman

No portrayal will likely match Jack Nicholson’s version of the Joker – a villain so weird, you can’t help but love him. Most of his lines were in the script, but Nicholson has admitted that his strange raspberry blow, flying bird exit from Vicki Vale’s apartment was complete improv, making us wonder where the script ended, and the real Joker began.

Gladiator

It’s hard to forget the opening battle of Ridley Scott’s Roman epic, but both he and star Russell Crowe knew that a quieter moment for Maximus was needed before the action started. The problem was, none had been written. While trying to come up with a solution, a bird decided to hop its way through the set. So Scott rolled the cameras, Crowe gave his reactions, and the rest is history.

The Lion King

It isn’t just live-action actors who get to improvise, either. When the time comes for Timon to cause a distraction to help Simba return to Pride Rock, actor Nathan Lane decided to add a joke suggestion of his own It turned out that was a better idea than what had actually been planned, meaning Timon wound up doing exactly that.

Alien

Ridley Scott wasn’t afraid to use tough love in getting the best from Sigourney Weaver, making sure her co-stars really did slap her instead of faking it. But to truly put her on edge, he instructed actor Yaphet Kotto to interrupt all of her lines. By the scene following Dallas’ death, she’d had enough, telling her co- star, not the character to “SHUT UP!”

The Dark Knight Rises

The villain Bane may have been terrifying, but you can’t say he didn’t have a sense of humor – or a softer side But Bane’s description of the young boy singing the national anthem at a Gotham football game was actually actor Tom Hardy’s, improvised on the spot.