James Lurie as Narrator (voice)

Seth Shostak as Self - SETI Institute

Nick Pope as Self - U.K. Ministry of Defense

Brian De Toy as Self - Director of Defense Studies, West Point

Stephen Hawking as Self - Theoretical Physicist (archive footage)

Paul Springer as Self - USAF Air Command and Staff College

Travis Taylor as Self - Physicist & Author

Bob Boan as Self - Co-Author, Alien Invasion: How to Defend Earth

Michael Michaud as Self - Author, Contact with Alien Civilizations

Paul Parsons as Self

John Ringo as Self - Author, Live Free or Die

Mark Moffett as Self - Author: Adventures Among Ants

Dirk Schulze-Makuch as Self - Washington State University

Neil Strauss as Self - Author, Emergency

Kevin Reeve as Self - onPoint Tactical

Quay Terry as Self - Gunnery Sergeant, USMC

Bill Brown as Self - High Altitude Research Corp.

Elise Cantu as Survivor

Carin Chea as Laboratory Scientist

Zee Cruise as Survivor

Leandro DiMonriva as Scientist

Kenneth Favell as Survivor

Philip Hersh as News Correspondent

Sydney Jay as Survivor

Christopher Clay Jones as Resistance Leader

Matt Lasky as Survival Expert

Eric Raymond Lim as Resistance Fighter

Desiree Martin as Survivor

Tiffany Martinez as Survivor

Richard Miraan as Astronomer

Jose Rosete as Survivor

David Schlachtenhaufen as Resistance Fighter

Christopher Warren as Agent Patterson

Avihai Yaffe as Survivor

Justin Cuomo as Human Resistance Leader