Chris Hemsworth's family appears in this film:
- Sons Sasha Hemsworth and Tristan Hemsworth play young Thor (at different ages).
- Daughter India Rose Hemsworth plays Gorr's daughter.
- Brother Luke Hemsworth plays a stage actor portraying Thor.
- Wife Elsa Pataky plays a former lover of Thor (the wolf woman in the opening sequence).
Christian Bale had initially turned down the possibility of appearing in any more comic book or superhero films after The Dark Knight Rises (2012), seeing the genre as uninteresting from an acting perspective, and especially finding the experience of donning the Batman costume to be a miserable one. He agreed to take part in this film however, having been impressed by Taika Waititi's previous works and after his kids begged him to take the role.
Natalie Portman told In a Total Film in a separate interview that Christian Bale looked terrifying while in costume. "The children would run screaming," she said. "He has a very, very, very scary look, in addition to, of course, his excellent acting. But, on this one, in between, he'd be like, 'Hey, what's up?' It was just a normal conversation, which was jarring, because he looked terrifying."
Chris Hemsworth, on his 8th time playing the character of Thor, achieved his biggest physique ever for this film, getting up to 231 pounds (105 kilos) for the role. His longtime trainer, Luke Zocchi said, "He is in phenomenal nick. He's the biggest he has ever been. He's the heaviest he's ever been." This extent of musculature required Hemsworth to eat at least 8 times a day during the entire duration of filming just to maintain all the muscle mass he had acquired.
Natalie Portman stood on platform boxes next to Chris Hemsworth to look taller next to him. Portman stands at 5' 3" (1.60 m) tall, while Hemsworth is a foot taller at 6' 3" (1.91 m).