Supernatural

Jared Padalecki as Sam Winchester
He attended Stanford University on a full-ride scholarship, and graduated with honors. But right before an interview with a prestigious law school, Sam's older brother, Dean, reappeared in Sam's life to tell him that their father had gone missing.

Jensen Ackles as Dean Winchester
Dean grew up along side his father, learning how to track and hunt demons. When his father dissappeared during a hunting trip, Dean went to Sam to convince him to help him find their father.

Katie Cassidy as Ruby
Ruby is a demon who tries to forge an alliance with the brothers. She helps the brothers from time to time. The reason for aiding the brothers was later revealed in season 3.

Lauren Cohan as Bela Talbot
A self-centered thief who steals occult objects and sell them to wealthy clients. She is a thorn to the Winchester brothers.

Jeffrey Dean Morgan as John Winchester
Sam and Dean's father. His mission is to find whoever or whatever it is that killed his wife. During his boys' childhoods, he raised them to be skilled demon hunters, teaching them techniques and methods that he had discovered.

Jim Beaver as Bobby Singer
Bobby is a hunter like the Winchesters, though he seems to stay fairly stationary. His customary attire usually consists of flannel and a trucker's hat. Bobby provides hunting and research support to the Winchesters.

Misha Collins as Castiel
As an angel, he possesses a number of superhuman abilities, including immortality, telekinesis, and the power to exorcise demons with his touch. He helps the brothers in their battles with various demons and angels.

Genevieve Cortese as Ruby
In season 4, Ruby's character has been replace by actress Genevieve Cortese due to budget contraint.