The ensemble cast of Ridley Scott's The Martian continues to grow as EW today reports that Mackenzie Davis (What If), Chiwetel Ejiofor (12 Years a Slave, and Sebastian Stan (Captain America: The Winter Soldier are joining Matt Damon, Jeff Daniels, Kate Mara, Michael Pena, Kristen Wiig, Jessica Chastain and Sean Bean for the science fiction tale.