Not only did Malcolm McDowell give the best performance of his career, but he also did so completely improvising. This impacted the actor’s personal life and even caused him to have seizures at night. In addition to that, he needed therapy during filming.
McDowell even suffered from temporary blindness. The actor had to be treated for insanity and was put on medication.
Bill Skarsgard – It
Playing a demonic clown is bound to create some problems with your mental state. Bill Skarsgard can certainly attest to this. The horrifying clown got a real upgrade when the actor took the reigns on this one. There is no denying the sheer terror when watching this film, which is surprising, considering the fact that he didn't have much experience beforehand.
Thanks to the film, the actor instantly shot to stardom. He now will forever be remembered as the greatest Pennywise ever. That fact remained true in the sequel.
Christian Bale – The Machinist
The actor is known for pushing the limits and immersing himself deep into certain roles, both physically and mentally. In the film "The Machinist", Bale played the hallucinating machinists with insomnia. He lost 60 pounds for the role, making himself completely emaciated. The actor didn't get much sleep either and would go for weeks fully awake.
The actor would also go as far as completely isolating himself from the outside world for months. All of this of course made his acting on the film absolute perfection.
50 Cent –All Things Fall Apart
The rapper proved that he is not just about the 2000s club hits, but also about serious acting. When he starred in the film "All Things Fall Apart" he made an effort to physically transform himself into an almost sickly version of himself.
This was done by sticking to a strictly liquid diet. The actor ended up weighing 160lbs after nine weeks of dieting. Sady, all that hard work didn't exactly pay off as the film ended up being a giant flop.
Johnny Depp – Pirates of The Caribbean
Being no stranger to controversy, Johnny Depp's time as the crazy Captain Jack Sparrow attracted a lot of media attention. The actor reportedly challenged Keith Richards from the Rolling Stones when playing the beloved character.
The acting proved to be successful as it ultimately became part of the first of many sequels. Only after the film wrap did he go back to being just plain old Johnny Depp.