Casting
In January 2010, Jason Momoa was selected for the role of Conan. Momoa beat Kellan Lutz and Jared Padalecki for the role. He was enrolled in an intense six-week training programme at a stunt and martial arts academy in Los Angeles for his part, while still finalising negotiations for the film. Momoa intended to add 10 pounds of muscle to his 215-pound frame, with the help of The Bourne Ultimatum's stunt performer David Leitch, and the martial arts stunt coordinator for The Matrix Reloaded and The Matrix Revolutions, Chad Stahelski.
Leo Howard was cast as the younger Conan in the film, as the first 15 minutes focused on Conan's youth.
The casting call for Conan's father, Corin, reveals the character to be "powerfully built, intelligent, graceful, master swordsman, skilled blacksmith, de facto leader of Cimmerians and Conan's father. He resolves to answer the terrible request of his dying wife and cuts Conan out of her so she can see him. He then shoulders the burden of raising Conan, which proves to be daunting given the boy's savage nature. Corin teaches his son the meaning of the sword: a hot blade must be cooled and tempered. When Khalar finally corners him and tortures him to death, he shows no regret nor pain, hiding his concern for his son's safety from the eyes of the enemy." Mickey Rourke first entered negotiations. Originally, talks had happened before but after a period of no talk, offers were returned to Rourke in February 2010. Rourke left the project for a second time, in apparent favor of the Immortals film. Ron Perlman took on the character in March 2010.
Bob Sapp portrays Ukafa, "a leader of Kushite Tribemen from the savannahs of Kush. Ukafa is Khalar Zym's second in command, jealous that Zym's daughter, Marique, will one day be warlord. He obeys his leader but plots the overthrow of his daughter. He is a mighty warrior and unbeatable in battle—until he meets Conan."
Rachel Nichols joined the cast as Tamara, described as "the Queen's servant, bodyguard and best friend. She and many other female bodyguards to the queen have been in hiding most of their lives because of the curse of Acheron, which would take the queen’s life to bring almost immortal power to its king. When Khalar Zym, a powerful warlord with ambitions to become the king of Acheron, storms the monastery and captures all of the novitiates, she is separated from Ilira, the one she must protect. With all of her strength and will, Tamara is determined to find and rescue her. She finds herself in league with Conan because of a mutual need to find Khalar Zym. She is not in the least intimidated by Conan’s size or grim demeanor and their alliance eventually blossoms into something that surprises them both."
Stephen Lang plays Khalar Zym, described to be "commanding in size and manner, a warlord and formidable warrior, brilliant, cruel, weathered and tanned by the many campaigns he has waged and won. He is driven in his quest to find the Queen of Acheron and has been building an empire to do so."
Rose McGowan also stars as "an evil half-human/half-witch", as announced by Variety in March 2010. She plays Marique, the daughter of Khalar Zym (Stephen Lang). Although the part was originally written as a male character called Fariq, McGowan impressed the producers with her take of the role, so her character was rewritten to be female. McGowan attempted to inject an Electra complex for the character, noting: “Initially, that obsession with trying to seduce her father was not scripted; it was something that the writer and I talked about quite a bit. But, unsurprisingly, the studio was freaked out by it. A lot of the dialogue that we’d come up with to support that, and really give it a deviant, complicated feel, had to be taken out. So I just figured, 'OK, then, I'll just act it and make it as uncomfortable as possible without any dialogue!'" When asked about preparation to play a witch, McGowan stated that her costume had significance in her preparation and that makeup for her character took 6 hours.
Dolph Lundgren had spoken to the producers in November 2009 about an unspecified role. This never came to fruition.