I Am Number Four (2011)

Aliens and their Guardians are hiding on Earth from intergalactic bounty hunters. They can only be killed in numerical order, and Number Four is next on the list. This is his story.
 
Director:  D.J. Caruso
Writers:  Alfred Gough (screenplay), Miles Millar 
Stars:   Alex Pettyfer, Timothy Olyphant, Dianna Agron