Hello. I am Castiel, the angel of Thursday. I am an angel of the Lord and a warrior in His name.

Many angels laid siege to Hell to rescue Dean Winchester, but it was Castiel who ultimately pulled Dean out. According to Castiel, he did so "because God commanded it". His hand print was burned into Dean's left shoulder.

Castiel is amongst a group of angels who manifest on Earth to stop the breaking of the The 66 Seals which will release Lucifer and start the Apocalypse. Over time he develops an empathy for the Winchesters, in particular Dean.

Castiel manifests on Earth through possession of a vessel - in his case Jimmy Novak. On one occasion, Castiel describes his true angelic form as a "multidimensional wavelength of celestial intent"; on another, he says that is true form the size of the Chrysler Building. Castiel's true voice, like the true voices of other angels, is piercing to the human ear.

Because he was an angel, Castiel initially expressed almost no emotion towards humans, and had little room for disobedience or feelings, as he was driven to follow his orders, although he does reveal some doubts about the morality of his orders. After his second resurrection by God, with enhanced abilities, he sees his decisions and support of freewill to have been affirmed.