In May, Atonement actress Saoirse Ronan signed on to lead the cast of the film, playing Melanie Stryder. Since then, Max Irons and Jake Abel have also joined the movie.
Chandler Canterbury and Boyd Holbrook have now also landed roles in the highly-anticipated film, according to Variety. Canterbury will play Melanie's little brother Jamie, while Holbrook will portray Abel's character's older brother Kyle.
In December, William Hurt was reported to be in talks for The Host. Should he sign on to the film, he will take the role of Jeb.
Last year, Ronan confessed that she'd love to work with director Quentin Tarantino.
The Host will open in cinemas on March 29, 2013.