Known Dark Ones
- Emma Swan - after absorbing the Darkness and becoming the Dark One, Emma spawns out of molten darkness from the vault.
- Killian Jones - upon becoming the Dark One, Killian also spawns from the Vault of the Dark One.
- Baelfire - uses the vault to bring back Rumplestiltskin, but eventually loses his own life.
- Guinevere - uses the vault to find a way into the Dark One's Pocket Dimension and find the Dark One's Dagger.
- Lancelot - uses the vault to return to the pocket dimension in order to hide the dagger.
According to Lumiere, the first Dark One was created in the vault out of the darkness. After the current Dark One, Rumplestiltskin, sacrifices his life by stabbing himself and Peter Pan with the Dark One's dagger, Baelfire and Belle meet Lumiere in the library while looking for a way to resurrect him. Lumiere tells them about the vault, and they obtain the key to unlock it. They travel and eventually come across the vault, but they find out that the Wicked Witch of the West wants them to bring back Rumplestiltskin so she can control him the dagger. Nonetheless, Baelfire unlocks the vault, and liquid darkness begins filling the vault. The darkness then gains shape, and forms into Rumplestiltskin. However, the rule of the vault is that it is a life for a life - whoever unlocks the vault and resurrects the Dark One, must die in his place. As Baelfire lays there, dying, Rumplestiltskin claims that he will not lose his son again, and magically absorbs Baelfire into his own body. However, it makes Rumplestiltskin insane, and in Storybrooke, Baelfire and Rumplestiltskin are magically separated by Emma Swan, causing Baelfire to die. Later, when the Darkness is removed from Rumplestiltskin and absorbed by Emma, she becomes the Dark One and respawns from the vault. The same process happens to Killian Jones.
- S3, E15: "Quiet Minds" (flashback)
- S5, E01: "The Dark Swan"
- S5, E04: "The Broken Kingdom" (flashback)
- S5, E08: "Birth" (flashback)
- S5, E10: "Broken Heart" (flashback)