Dean Winchester.

Demon Dean (also known as Deanmon or Dark Dean) is the infernal alter ego of Dean Winchester, awakened within his body by the influence of the Mark of Cain. He became Crowley's right-hand man.

The familiar tousled hairstyle was replaced by slicked-back hair, and Dean traded his iconic plaid shirts for an elegant burgundy one. The biggest visual change was his completely black, demonic eyes.

Unlike ordinary demons, possessed by centuries-old malice, "Demon Dean" was essentially himself, but devoid of guilt, fear, and conscience. He was Dean Winchester, whose worst character traits (arrogance, hedonism, selfishness, and cruelty) were exalted to the extreme. He had absolutely no regard for those around him, including his younger brother, Sam.

As a demon (and a Knight of Hell), he possessed superhuman strength, agility, and invulnerability. A natural-born and ruthless hunter, he became a deadly weapon, his fighting instincts unleashed without mercy or remorse.