Robert Naylor
The Scythe / Spencer (16 eps)
Billy Campbell
Dr. Alan Farragut (13 eps)
Meegwun Fairbrother
Daniel Aerov (13 eps)
Jordan Hayes
Dr. Sarah Jordan (13 eps)
Mark Ghanimé
Major Sergio Balleseros (13 eps)
Neil Napier
Dr. Peter Farragut (13 eps)
Kyra Zagorsky
Dr. Julia Walker (13 eps)
Cat Lemieux
Dr. Doreen Boyle (13 eps)
Hiroyuki Sanada
Dr. Hiroshi Hataki (13 eps)
Jeri Ryan
Constance Sutton (3 eps)
Christian Jadah
Lt. Klein (3 eps)
Tamara Brown
Dr. Sulemani (2 eps)
Patrick Baby
Dr. Duchamp (1 eps)