According to Variety, Chris Hemsworth and Clifton Collins Jr. have booked roles in the Paramount feature.
Hemsworth will play George Kirk, father of James Kirk. Since Hemsworth is a 24-year-old Australian, it's probably that any paternal feelings he might show for the future Enterprise captain will be in flashbacks, since 27-year-old Chris Pine is playing James Kirk for most of the movie.
Collins, meanwhile, will play Ayel, a cohort of Eric Bana's evil Nero.
Also on board are Karl Urban as Young Bones, Zoe Saldana as Young Uhura, John Cho as Young Sulu, Simon Pegg as Young Scotty and Anton Yelchin as Young Chekov.
Alex Kurtzman and Roberto Orci scripted the new "Star Trek," expected to focus on the early adventures of the Enterprise gang post-Starfleet Academy. [More specific rumors about the plot have been reported online, but we won't go into rumors, spoilers or speculation.]
An Emmy nominee for "Thief," Collins was part of the SAG Awards-winning ensemble of "Traffic" and the SAG Awards nominated ensemble of "Capote."
Some folks (Australian folks) may know Hemsworth from the soap "Home and Away," but probably not many.