William Hurt as Professor Eddie Jessup

Blair Brown as Emily Jessup

Bob Balaban as Arthur Rosenberg

Charles Haid as Mason Parrish

Thaao Penghlis as Echeverria

Miguel Godreau as Primal Man

Dori Brenner as Sylvia Rosenberg

Peter Brandon as Hobart

Charles White-Eagle as The Brujo

Drew Barrymore as Margaret Jessup

Megan Jeffers as Grace Jessup

Jack Murdock as Hector Orteco

Francis X. McCarthy as Obispo

Deborah Baltzell as Schizophrenic Patient

Evan Richards as Young Rosenberg

Paul Larsson as Charlie Thomas

John Larroquette as X-Ray Technician

George Gaynes as Dr. Wissenschaft

Hap Lawrence as Endocrinology Fellow

John Walter Davis as Medical Technician