The quintet join Richard Jenkins and Bradley Whitford, who were cast in the horror movie in January. Plot details for the MGM/United Artists film, which marks Cloverfield writer Goddard's directorial debut, are being kept secret.
"Finding this ensemble has been very hard and very rewarding," producer Whedon told The Hollywood Reporter. "Each of the 'kids' is unique, fascinating and talented, and like true friends, the group is more than the sum of its parts.
"These are people you care about, able to go toe to toe with the amazing actors we've corralled thus far, and not unpretty in the bargain. I can't wait to harm them."
The Cabin In The Woods will be released on February 5, 2010.