Where acting is concerned, preparation is key, as even the least-demanding role requires an actor to turn up to set with their lines learned and in appropriate physical condition to play their part.
But sometimes, for one of many reasons, an actor shows up ready to film having prepared in the entirely wrong way.
Perhaps there was a miscommunication with the director or they simply chose to make a cavalier creative choice without informing anyone, ensuring the cast and crew alike were shocked when they rocked up looking or acting how they did.
These 10 actors, from certified legends of the industry to young up-and-comers, all ended up preparing totally wrong for a role, from learning the wrong accent to bulking up too much, doing some misguided research, or even just shaving their whole beard off.
In many cases this caused issues on set and forced the filmmakers to pivot their original plans, coming up with a quick solution to ensure that filming as a whole wasn't impacted.
Whether you noticed it or not in the final film, these actors weren't nearly as prepared as you might've expected...
10. Ian McKellen Learned The Wrong Accent - The Keep
Ian McKellen is about as much of a pro as actors get - a venerable gem of the old guard who's never phoned in a performance. Not even once. Probably.
But in a recent interview with Variety, he revealed that a "miscommunication" between himself and director Michael Mann on 1983's cult horror film The Keep led to him learning the wrong accent for the part.
According to McKellen, Mann told him to develop a Romanian accent to play the role of Jewish history professor Dr. Theodore Cuza, prompting McKellen to characteristically whole-ass the job by visiting Romanian and getting first-hand experience to learn the accent.
But when the actor finally made it to set for the first day of shooting, Mann told him to instead play Cuza with a Chicago accent, which caused friction between the two.
McKellen wasn't prepared to play the part with a twang from the Windy City, and so basically opted for a broader "generic American" accent.
Combined with the hours he had to spend in the makeup chair each day in order to appear older, McKellen called The Keep his worst moviemaking experience.