David Duchovny

Agent Fox Mulder

Gillian Anderson

Agent Dana Scully

Mitch Pileggi

Assistant Director Walter Skinner

William B. Davis

The Cigarette-Smoking Man

John Neville

The Well-Manicured Man

Martin Landau

Kurtzweil

Jeffrey DeMunn

Bronschweig

Tom Braidwood

Frohike

Blythe Danner

Cassidy

Terry O'Quinn

Michaud

Dean Haglund

Langly

Bruce Harwood

Byers

Armin Mueller-Stahl

Strughold

Lucas Black

Stevie

Cody Newton

3rd Boy

Don S. Williams

Group Elder

George Murdock

2nd Elder

Michael Shamus Wiles

Black-Haired Man

Darrell Davis

Primitive #1

Tom Woodruff Jr.

Creature #1

Ted King

FBI Agent on Roof

Steve Rankin

Field Agent

Gary Grubbs

Fire Captain Cooles

Steven M. Gagnon

Last Agent Out

Larry Joshua

DC Cop

Gunther Jenson

Security Guard

Scott Alan Smith

Technician

Ian Ruskin

Well-Manicured Man's Valet

Michael Krawic

2nd Paramedic

Larry Rippenkroeger

Towncar Driver

Josh McLaglen

Buzz Mihoe

Randy Hall

Windbreakered Agent

Vanessa Morley

Young Samantha Mulder (archive footage)

Jason Beghe

FBI Man at Bomb Site (uncredited)

Glenne Headly

Barmaid (uncredited)