Hemsworth will play Captain Kirk's father, George Kirk. Collins will play Ayel, the cohort and general to Nero, played by Eric Bana.
The duo joins the previously cast Zachary Quinto, Chris Pine, Simon Pegg, Karl Urban, Bana and Winona Ryder.
Filming began last week. Alex Kurtzman and Roberto Orci wrote the script about the Starfleet Academy days of the crew of the Starship Enterprise.