The 26 Best Unscripted Moments In Movie History

Every movie starts with a screenplay. But because filmmaking is a collaborative process, a script is frequently altered during production, whether it's by the writer, the director, or the actors involved. What sounds good on the page doesn't always work once it gets in front of the camera, and there have been plenty of iconic movie moments that weren't even in the script — the best of which we cover in our video right above.

Often times, these improvised moments are simple quips or ad-libbed lines that an actor throws in while shooting a scene. Even if the movie's writer doesn't like the change, the director might feel that it works better than what was written, or even encourage some improvisation when a scene isn't working. Some directors, like comedy specialists Adam McKay or Taika Waititi, have been known to favor improv. After all, humor isn't always something that can be created by simply sitting at a desk with a typewriter — it often happens in the moment.

But it's not just comedies; some of the most famous improvised moments in film have come in tense dramas, horror movies, or even science fiction — the kinds of stories that require a lot of thought and careful planning. Nevertheless, new ideas flow on the set, and sometimes it's best to let a scene breathe life into itself in real time — which sometimes leads to cinematic gold.

Hollywood history is littered with classic lines that left a lasting impression on audiences. But it might come as a surprise to learn that some of the most famous utterances that have stuck with us for decades were the result of an on-set ad-lib. Take, for example, the single most romantic moment in the entire "Star Wars" saga, when Princess Leia professes her love for Han Solo just as he's about to be frozen in carbonite in "The Empire Strikes Back." Harrison Ford's solemn reply, "I know," was Ford's own idea, as he was unhappy with the scripted response.

Ford has a history of improv, also coming up with the single gunshot that ends his duel with a swordsman in "Raiders of the Lost Ark." Superstar Jack Nicholson has done it too: that legendary moment in "The Shining" where Jack Nicholson peers through a shattered hole, grinning like a psychopath? Well, Nicholson improvised the line "Here's Johnny!" on the day — much to director Stanley Kubrick's confusion, as he'd never seen Johnny Carson's "The Tonight Show."

As noted earlier, improvisation has become such a part of Hollywood filmmaking that some directors encourage it. That was the case with Martin Scorsese while filming one of the most famous scenes in "Taxi Driver," where Robert De Niro was told to come up with his own line while practicing his tough talk in a mirror. "You talkin' to me?" he says in one of the most memorable moments in movie history, and it was all ad-libbed. But that's just the tip of the iceberg, so check out our video for more of the most famous improvised lines in movie history.