Season One Guest stars

A
Tony Amendola as Barcelo
David Anders as Mr. Sark

Michelle Arthur as Abigail

Edward Atterton as Danny Hecht
Jack Axelrod as Giovanni Donato
John Aylward as Davenport

B
Tobin Bell as Dreyer
Peter Berg as Noah Hicks
Philippe Bergeron as Lucques Trepanier
Daniel Betances as Pearson
Ben Bray as Tchen
Agnes Bruckner as Kelly McNeil

C
Maurice Chasse as Jacqnoud
Robert Clendenin as Kostia Bergman
Greg Collins as Kenny
Lindsay Crouse as Evans
John Curry as Phillips

D
Allison Dean as Stephanie Campbell
Peter Dennis as Prof. Bloom
Neil Dickson as John Smythe
Lisa Dinkins as FBI Agent Baker
Nancy Dussault as Mrs. Calder

E
Tom Everett as  Kelvin

F
Al Farris as Salim Wahid
Yvonne Farrow as Diane Dixon
Cosimo Fusco as Logan Gerace

G
Mark Galasso as Ed Davis
Jay Gerber as Professor Mizzy
Haley Gilbert as Rachel
Maurice Godin as Agent Fisher
Greg Grunberg as Eric Weiss
Castulo Guerra as Briault
Carole Gutierrez as Laura Stenson

H
Zuhair Haddad as Sayyad
Timothy Halligan as Dr. Mallaska
Michael Halsey as Prof. Hoyt
James Handy as Devlin
John Hannah as Shepard
Arabella Holzbog as Laura Bristow
Lori Heuring as Kate Jones/Eloise Kurtz

I
Aharon Impale as Hassan
Amy Irving as Emily Sloane

Ravil Issyanov as Karpachev

J
Igor Jijikin as Chopper

K

Nicholas Kadi as Algosaibi

Elaine Kagan as Jane Litvack

Charles Keating as Alain Christophe
Kristoff Konrad as Endo
Dennis Keifer as Ferroq

Boris Lee Krutonoq as Khasinau (20 years ago)

Subash Kundanmal as Patel

Alex Kuz as Shcherbakov

L
Timothy Landfield as Kretchmer
Eugene Lazarev as Kreshnik
Dave Lea as Ice

James Lew as  Li Quan

Paul Lieber as Agent Calder

Stephen Liska as Ilyich Ivankov
Kamala Lopez Dawson as Dr. Shah

Scott Ellis Loring as Agent Gordon

M
Alec Maray as Sial
Luis Medina as Eduardo Benegas
Kevin Mitnick as Agent Burnett

Roger Moore as Edward Poole

Wolf Muser as Ramon Vesolo

N
Miguel Najera as Agent Gonzalez

O

Derrick O' Connor as Khasinau

Terry O' Quinn as FBI Agent Kendall

Jorgo Ggenenovski as Kessar
Ken Olin as  David McNeal

P

Patrick Pankhurst as Brandon Dahlgren

Evan Dexter Park as Charlie
Scott Paulin as Robert Stoller
Natasha Pavlovich as young Laura Bristow

R
Seema Rahmani as Sara

Bryan Rasmussen as Officer Cohen

Mark Rolston as Lambert

Q

Francesco Quinn as Minos Sakkoulas

S
Miguel Sandoval as Russek

Angus Scrimm as McCullough

Sarah Shahi as Jenny

Jon Simmon as FBI Officer Kendall

Stephen Spinella as Kishell

Joey Slotnick as Haladki

David St. James as Lucques Franco

T

Faran Tahir as Bak Ibrahim

Quentin Tarantino as McKenas Cole

Frank Hoyt Taylor as FBI Agent Dunn

Christopher Thornton as Nevil

Don Took as Agent Grey
Gina Torres as Anna Espinosa

Jennifer Tung as Toni

V

Scott Vance as Agent Douglas

W
James Warwick as Severn Driscoll
Norbert Weisser as  Schiller

Patricia Wetting as Dr. Barnett

Nancy Wetzel as Amy Tippin

Bernard White as Malik Sawari

Richard F. Whiten as Officer Pollard

Jeff Wolfe as Gonov

Y

Keone Young as Professor Choy

Del Zamora as Mike "The Mechanic"

Season Two Guest Stars

A
Dayna Adams as receptionist
Carol Androsky as NA moderator
Michelle Arthur as Abigail
Amy Aquino as Agent Virginia Kerr
B
Dato Bakhtadze as Russian security guard
Weston J. Blakesley as barfly
C
Mark Colson as ops director
D
Scott Donovan as American tourist
E
Chris Ellis as Agent Chapman
F
Daniel Faltus as Jan Spinnaker
Daniel Faraldo as Manolo
G
Strahil Goodman as techie no. 2
Greg Grunberg as Agent Weiss
Joel Guggenheim as agent-on-call
H
James Handy as Devlin
Jim Hanna as Claus Richter
Chris Harrison as reporter no. 2
Ira Heiden as techie
Endre Hules as Mr. Vashko
I
Amy Irving - Emily Sloane
J
K
Todd Karli as newscaster
Tom Kiesche as Agent Cooper
L
Clayton Landey as CIA Agent Wilcox
James Lesure as Agent Craig Blair
Keith Lewis as Agent Novak
Roger Lim as Taiwanese gasping body
M
Janet MacLachlan as Jane Banks
Stephen Markle as Senator Douglas
Victor McCay as Agent Rudman
Jamie McShane as CIA agent
Stephen Mendillo as Henry Fields
Paul Mendoza as bartender
Ilya Morelle as techie no. 1
Alex Morris as homeless vet
N
Marisol Nichols as Rebecca Martinez
Tricia Nickell as reporter no. 3
O
Derrick O'Connor as Khasinau
Cliff Olin - Cliff
Terry O'Quinn as Kendall
P
Kavita Patil as desk attendant
Sarah K. Peterson - young Sydney
R
Danny Romero as reporter no. 1
Q
S
Vladimir Skomarovsky - Kholokov
Kevin Sutherland as CIA operative
T
Austin Tichenor - Doctor Nicholas
Don Took as Agent Grey
V
W
Patricia Wettig as Barnett
Petra Wright as Alice
Y
Stuart Yee as the tester
Z