Hollywood loves a story about a star who walks out and a replacement who saves the day overnight. The reality is messier. Studios usually spend days or weeks recasting, and many famous exits were firings, injuries or scheduling clashes, not dramatic walkouts.
The eight roles below all changed hands in the middle of a production or right before cameras rolled. Where a timeline is documented, it’s stated plainly. Where it isn’t, the entry doesn’t claim a precise turnaround.
Predator: Kevin Peter Hall Replaces Jean-Claude Van Damme

Van Damme was originally attached to the creature suit. He told the crew that the stunts they wanted were impossible in the suit, and he left the production. Another account says he quit after two days of production.
The exit led to a rethink of the whole creature. The original footage was deemed unusable, and after the suit was redesigned, Kevin Peter Hall was recast. The fix took a redesign, so it was not an overnight swap.
Apocalypse Now: Martin Sheen Takes Over as Captain Willard

Harvey Keitel was the first Willard, and Francis Ford Coppola decided to replace him. Coppola quickly recast the role with Martin Sheen, who first appeared on set just ten days after Keitel departed.
Ten days is fast for a production of that scale. It still falls well outside a single day, so the film is a good example of speed that stops short of the headline.
V for Vendetta: Hugo Weaving Steps Behind the Mask

James Purefoy was originally cast as V, the masked revolutionary. No reasons were given at the time, though it was later reported that he quit over frustration with his costume.
Hugo Weaving replaced him. He re-recorded all of the dialogue, and his face never appears on screen. No exact timeline for the recasting is reliably documented.
X-Men: Hugh Jackman Becomes Wolverine

The role was first given to Dougray Scott. His participation was held up by production delays on Mission: Impossible II.
Jackman was brought in at the last minute. He became a household name when he landed the part. It’s one of the best known late replacements, though sources don’t pin it to a specific 24 hours.
Batman Returns: Michelle Pfeiffer Becomes Catwoman

Annette Bening had won the role first. After costume fittings and the start of filming, Pfeiffer was brought in to replace Bening, who didn’t want to reveal that she was expecting.
Bening’s departure was about pregnancy, not a stormy exit. Pfeiffer’s version of the character became one of the franchise’s best remembered.
Despicable Me 2: Benjamin Bratt Voices El Macho

Voice roles get swapped too. Al Pacino was set to play the villain El Macho, but after recording all his lines he left, citing creative differences.
Benjamin Bratt landed the part. There was no on set walkout here, since the work happened in a recording booth.
There Will Be Blood: Paul Dano Takes Eli Sunday

Kel O’Neill was the original Eli Sunday. According to The New York Times Magazine, he had to be replaced about halfway through the film’s 60 day shoot.
Paul Anderson’s film then went forward with Paul Dano in the part. There were reports that O’Neill suffered from intimidation, presumably from Daniel Day-Lewis’s method approach. The replacement came well after the cameras started rolling, not in a day.
A League of Their Own: Geena Davis Becomes Dottie

Debra Winger was originally cast as Dottie, a role ultimately played by Geena Davis. Winger trained with the Chicago Cubs for three months before quitting the production after Madonna joined the cast.
Davis went on to define the character for a generation of viewers. Winger’s departure was a real walkout, though sources here don’t give a precise recasting timeline.