The Harry Potter films are some of the most beloved in cinema history, carefully adapted from J.K. Rowling’s best-selling novels. But while the scripts were tightly written, not every memorable moment came directly from the page.
A fact most fans would find amusing is that some of the saga’s funniest, most emotional, and surprisingly heartfelt moments actually came from the actors themselves. Whether it was a quick-witted quote or dialogue, a spontaneous gesture, or a piece of dialogue added in the heat of filming, these unscripted moments brought depth, humor, and authenticity to the Wizarding World.
Fitting in perfectly with Rowling’s carefully crafted magical mayhem, here are 7 times that Harry Potter actors improvised scenes that made it into the movies!
7. Hermione and Ron’s Awkward Handshake — Harry Potter and the Chamber of Secrets
After Hermione is cured of being petrified, she excitedly hugs Harry, then hesitates with Ron and ends up shaking his hand rather than hugging. This was not a scripted moment but rather an improvisation by Emma Watson.
The actress didn’t want to hug both boys in front of so many extras/actors and felt shy, so she hugged Harry and only shook Ron’s hand. She was, in fact, pretty angry at the director Chris Columbus for making her run through the Great Hall and hug the boys (see Instagram).
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However, the moment ended up fitting perfectly with Ron and Hermione’s chemistry and eventual love story. It was awkward in a sweet way, and it foreshadowed Hermione’s more complicated feelings for Ron, and added realism to the trio’s dynamic.
6. Draco Malfoy’s “I Didn’t Know You Could Read” — Harry Potter and the Chamber of Secrets
During a scene where Draco Malfoy takes a jab at Goyle (actually Harry in disguise with Polyjuice Potion), Tom Felton ad-libbed the cutting remark: “I didn’t know you could read.”
The line wasn’t in the script, but Felton’s delivery was so perfectly Malfoy that the crew kept it. The moment cemented Draco as the sneering bully we love to hate and showed Felton’s sharp instincts as a young actor.
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Considering that Felton was around 13 years only at that time, the line is now counted as one of the most iconic moments of the series. Fans also often cite this as one of the funniest improvised moments in the series.
5. Lucius Malfoy “Let us hope Mr. Potter will always be around to save the day” / “Don’t worry. I will be.” — Harry Potter and the Chamber of Secrets
At the end of Chamber of Secrets, Lucius Malfoy, angry at Harry, says, “Let us hope Mr. Potter will always be around to save the day.” Harry, without missing a single beat (played by a young Daniel Radcliffe), replies, “Don’t worry. I will be.”
Reportedly, Jason Isaacs improvised this line, his reasoning being that this is something his character would say at that moment. However, he did not expect the young Radcliffe to reply and was, in fact, taken aback by his improvisation.
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The line perfectly captures Harry’s knack for being selfless and saving others. It is certainly heroic, memorable, and sets up Harry’s character arc.
4. Hermione Granger “Holy crickets, you’re Harry Potter!” — Harry Potter and the Sorcerer’s Stone
When Emma Watson’s Hermione first meets Harry and Ron on the Hogwarts Express, she belts out, “Holy crickets, you’re Harry Potter!” upon seeing Harry’s scar. Having reached their train carriage while helping Neville to find his pet frog, her reaction was not in the script.
Watson, as Collider reported, improvised the phrase “Holy crickets…” at the director Chris Columbus’s request to use “Holy ___!” and fill in something that felt right. She chose “crickets.”
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With time, the phrase has become perfectly in line with young Hermione and fits right in. Capturing her excitement, precociousness, and awkward energy, it also established her character in just one moment.
3. Hermione Granger’s “Emotional range of a teaspoon” — Harry Potter and the Order of the Phoenix
Harry Potter’s first love with Cho Chang was rather awkward and full of awkward teenage hormones. Cedric’s death further made it hard for them to really connect despite their mutual attraction.
So when Harry had his first-ever kiss in Order of the Phoenix, it was anything but nice. When he ends up discussing it with Ron and Hermione, confused by how Cho reacted and cried the entire time, Ron declares something like “One person couldn’t be feeling all that, they’d explode.”
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Just then, Hermione retorts, “Just because you’ve got the emotional range of a teaspoon…” While the line wasn’t an improvisation, it was the aftermath where the trio started giggling. Reportedly, Emma Watson couldn’t help but crack up at her own line, which made Daniel Radcliffe and Rupert Grint break character, too. Their reaction was just so pure and genuine that the director decided to keep it in the film.
2. Bellatrix Tortures Hermione — Harry Potter and the Deathly Hallows: Part 1
Few Harry Potter moments are as genuinely harrowing as the Malfoy Manor sequence in Deathly Hallows: Part 1. When Bellatrix Lestrange pins Hermione to the floor and carves Mudblood into her skin with a knife, the scene takes on a chilling realism that unsettled both audiences and even those on set.
What makes this moment so intense is that much of it wasn’t even tightly scripted, but director David Yates let his actors improvise. In an interview with Fandango, he revealed that he deliberately gave Helena Bonham Carter (Bellatrix) and Emma Watson (Hermione) freedom to explore the scene. The result was a raw, unscripted exchange that felt chaotic and unpredictable.
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Even the director himself admitted that the scene was scary and horrible to listen to during filming. This improvisational choice gave the overall torture sequence its disturbing edge.
1. Arthur Weasley and the Rubber Duck Question — Harry Potter and the Chamber of Secrets
Chamber of Secrets alone gave us a lot of unscripted moments, but the best of them was when Harry meets Arthur Weasley at the Burrow. Too fond of everything Muggle, he promptly asks him, “What exactly is the function of a rubber duck?”
Reportedly, this was one of the many questions that the actor Mark Williams improvised. In every take, he continued to ask more such absurd yet interesting questions, and the rubber duck version ultimately made it to the final cut.
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During a 2016 Leviosa fan event, Chris Rankin, who starred as Percy Weasley, revealed this interesting tidbit (via BuzzFeed). The line today is one of the best improvisations of the saga. It is funny, it is whimsical, and it fits Arthur’s character perfectly.
Well, the magic of Harry Potter didn’t just come from spells and effects, but much of it was due to the cast breathing life into their characters. Now that you have reached the end of this list, let us know in the comments below which is your favorite moment that was improvised by the cast.
The Harry Potter franchise is available to stream on HBO Max or can be rented on Prime Video.