David Duchovny

Character: Dr. Ira Kane

Julianne Moore

Character: Dr. Allison Reed, CDC

Orlando Jones

Character: Prof. Harry Phineas Block

Seann William Scott

Character: Wayne Grey

Ted Levine

Character: General Russell Woodman

Ty Burrell

Character: Colonel Flemming

Ethan Suplee

Character: Deke

Michael Bower

Character: Danny

Dan Aykroyd

Character: Governor Lewis

Gregory Itzin

Character: Cartwright

Pat Kilbane

Character: Officer Johnson

Sarah Silverman

Character: Denise

Michelle Wolff

Character: Carla

Katharine Towne

Character: Nadine

Stephanie Hodge

Character: Jill Mason

John Cho

Character: Student

Steven Gilborn

Character: Judge Guilder

Wayne Duvall

Character: Dr. Paulson

Kyle Gass

Character: Officer Drake

Jerry Trainor

Character: Tommy

Jennifer Savidge

Character: Clare

Wendy Braun

Character: Nurse Tate

Michael Chapman

Character: Sheriff Long

Mary Pat Gleason

Character: Customer

Andrew Bowen

Character: Road Worker

Chris Wylde

Character: Student

Tom Woodruff Jr.

Character: Lead Primate Creature (uncredited)

Ashley Clark

Character: Lt. Cryer