Tomorrow, When the War Began is a 2010 Australian action-adventure war drama film written and directed by Stuart Beattie and based on the 1993 novel of the same name by John Marsden. The film was produced by Andrew Mason and Michael Boughen. The story follows Ellie Linton, one of seven teenagers waging a guerrilla war against an invading foreign power in their fictional hometown of Wirrawee. The film stars Caitlin Stasey as Ellie Linton and features an ensemble cast including Rachel Hurd-Wood, Lincoln Lewis and Phoebe Tonkin. Production began in September 2009.

Stuart Beattie is an Australian filmmaker. His screenplay for Collateral (2004) earned him nominations for the BAFTA Award for Best Original Screenplay, Satellite Award for Best Original Screenplay and Saturn Award for Best Writing.