- Luis Elizondo - Self – Former Counterintelligence Agent
- Kirsten Gillibrand - Self – Senate Armed Services Committee
- John A. Samford - Self – Dir. of Intelligence, U.S. Air Force (archive footage)
- David Fravor - Self – Former Navy Pilot
- John Podesta - Self – Former White House Chief of Staff
- Harry Reid - Self – Former Senate Majority Leader
- Ralph Blumenthal - Self – Former Staff Reporter, New York Times
- Seth Shostak - Self – Sr. Astronomer, SETI Institute
- Neil deGrasse Tyson - Self – Director, Hayden Planetarium
- Derrick Pitts - Self – Chief Astronomer, The Franklin Institute
- George W. Bush - Self (archive footage)
- Barack Obama - Self (archive footage)
- Harold Brown - Self – Secretary of the Air Force (archive footage)
- Mark O'Connell - Self – Author, J. Allen Hynek Biography
- J. Allen Hynek - Self – Scientific Advisor to Project Blue Book (archive footage)
- Robert Salas - Self – Retired Air Force Captain
- Jimmy Carter - Self (archive footage)
- Steven Spielberg - Self (archive footage)
- Jacques Vallée - Self – Astronomer & Internet Pioneer
- Linda Zimmermann - Self – Author, 'Hudson Valley UFOs'
- Richard F. Haines - Self – Chief Scientist, NARCAP Retired
- James Fox - Self – Filmmaker
- John Callahan - Self – FAA Division Chief, Retired 2011
- Joe Biden - Self (archive footage)
- Marco Rubio - Self – Senate Intelligence Committee Vice Chairman
- Tim Burchett - Self – Tennessee, 2nd District
- Garry Nolan - Self – Professor, Stanford University Dept. of Pathology
- Avi Loeb - Self – Astrophysicist, Harvard University
- Jeff Bezos - Self (archive footage)
- Michio Kaku - Self – Theoretical Physicist
- Leslie Kean
- Jonele Conceicao
- Kate Lewin Hilgenberg
- Ricki Stern
- Mo Krishna
- Meghan O'Hara
- Ceiri Torjussen
Chris Mellon interpreta a Self – Former Deputy Asst. Secretary of Defense for Intelligence en la serie.
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