Boy Kills World director Moritz Mohr initially had reservations about casting Bill Skarsgård in the lead role of the action-packed movie. Known for his work in drama and horror films like the It adaptations, Skarsgård took on a new challenge as a deaf-mute martial artist seeking vengeance for his family's murder in Boy Kills World.
Despite doubts about Skarsgård's ability to handle the physical demands of the role, the actor impressed Mohr with his dedication to training and mastering fight choreography. Mohr praised Skarsgård's commitment, noting that he exceeded expectations and delivered a phenomenal performance in the film.
