Season 1 established the show's core formula and introduced the foundational creature lore. Sam and Dean Winchester reunite after their father John goes missing, and they hit the road investigating supernatural cases while searching for the Yellow-Eyed Demon (Azazel) responsible for their mother's death.
Creatures Introduced
The first season cast a wide net across world folklore, introducing a new creature type nearly every episode. Key introductions include: the Woman in White (pilot episode), the wendigo, Bloody Mary (as a vengeful ghost variant), shapeshifters, the Hook Man (another ghost variant), insects controlled by a Native American curse, the shtriga, the rawhead, reapers, vampires, and various ghosts. The season established salt, iron, and the salt-and-burn as the baseline hunting toolkit.
Major Lore Developments
The Colt was introduced as a legendary weapon that can kill almost anything. The yellow-eyed demon Azazel was established as the primary antagonist and the being responsible for the Winchester family tragedy. Demon mythology was expanded to include crossroads deals, demonic omens (cattle deaths, electrical storms, temperature fluctuations), and the Latin exorcism rite. The existence of psychic children — humans with supernatural abilities triggered by Azazel's blood — was foreshadowed.
Tone & Approach
Season 1 is the most purely monster-of-the-week season, with each episode largely self-contained. The creature designs lean toward classic horror — dark, isolated settings, vulnerable victims, and a clear threat to identify and destroy. The lore is kept relatively simple, with most creatures having straightforward weaknesses. The emotional core is the relationship between Sam and Dean and their search for their father.