Daniel North and Elijah Grey are the only known Revenants in the Faceless Universe.
Once Daniel and Elijah were exposed to a higher amount of the Sorrowvirus than allowed, they cursed themselves to a fate worse than death, the ability to never age. However, due to very complex scenarios, the exposure to the Sorrowvirus, their presence in Purgatory and their conflict with the Being, their eventual deaths would lead to them disintegrating, before returning as a metaphysical entity known as a Revenant. Due to the extremely unlikely circumstances that caused this to happen, these two are the only Revenants known to exist. Since there is none of the Sorrowvirus left, it is impossible for another Revenant to exist, because that was the crucial element that caused the change. Daniel and Elijah's souls are dead, but they have returned in an almost psychopathic form, with little to no emotions.