Zoso was the former Dark One, and like all other Dark Ones before him, he tried to obtain the Sorcerer's Hat. After defeating the Sorcerer's Apprentice in battle Zoso attempts to take the device that, when activated, turns into the hat. However, it has an enchantment that repels Zoso, since anyone who has succumbed to darkness is unable to obtain it. Having failed his goal, he leaves, enraged. Disguising himself as an old peddler, he comes across Rumplestiltskin, who is taking his son Baelfire away from their village because Hordor and the other knights are starting to collect young people to fight in the Ogres War. He tells Rumplestiltskin of a mystical dagger which can be used to control the Dark One. Rumplestiltskin forms a plan, and sets part of the Duke's castle on fire. He then sneaks in and steals the dagger. Rumplestiltskin eventually summons the Dark One, Zoso, but when Zoso keeps tormenting him about his son, Rumplestiltskin stabs him in the chest. Zoso reveals himself to be the old peddler, who wanted to be stabbed so that he could finally move on from his miserable life fraught with darkness. Due to the Dark One's Curse, Rumplestiltskin takes Zoso's place as the new Dark One.
After Hook uses the blood of Rumplestiltskin to open a portal to the Underworld, Zoso and the other previous Dark Ones arrive at Storybrooke. Zoso and the other Dark Ones are banished and absorbed into Excalibur.
- None known (family)
- Zoso was one of the oldest people in the Enchanted Forest, although not as old as Merlin or the Apprentice. It is unknown exactly how long he had lived as the Dark One, but it can be assumed that he was older than Rumplestiltskin.
- S1, E08: "Desperate Souls" (flashback)
- S4, E04: "The Apprentice" (flashback)
- S5, E07: "Nimue" (hallucination)
- S5, E10: "Broken Heart"
- S5, E11: "Swan Song"