Corey Stoll
Dr. Ephraim Goodweather

Kevin Durand
Vasiliy Fet

Miguel Gómez
Augustin 'Gus' Elizalde

David Bradley
Professor Abraham Setrakian

Jonathan Hyde
Eldritch Palmer

Richard Sammel
Thomas Eichorst

Max Charles
Zach Goodweather

Ruta Gedmintas
Dutch Velders

Natalie Brown
Kelly Goodweather

Mía Maestro
Dr. Nora Martinez

Robin Atkin Downes
The Master (voice)

Rupert Penry-Jones
Mr. Quinlan

Jack Kesy
Gabriel Bolivar / The Master

Sean Astin
Jim Kent

Samantha Mathis
Justine Feraldo

Robert Maillet
The Master / The Master / Jusef Sardu

Anthony Grant Lake
Strigoi (uncredited) / Strigoi

Roger Cross
Reggie Fitzwilliam

Joaquín Cosío
Angel Guzman Hurtado

Jamie Hector
Alonso Creem / Alonso Creem (uncredited)