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Catharis, Matron of Crucibles, is a Super Unique Death Maiden in Act V of Diablo III. She operates the Master Soul Crucible in the Nobles' Rest Courtyard during the Souls of the Dead quest, and only appears in Campaign Mode.

In combat, she is initially shielded from harm, and only becomes vulnerable with the destruction of all six corpse piles surrounding the crucible. She has Fast and Electrified traits, and in addition attacks with hordes of Reapers, which are summoned both by herself and by the crucible. Kiting her to the back of the row makes the fight easier by distancing it from the summon location of some of the Reapers.

Catharis's Soul Crucible is the largest and last one in the city of Westmarch. It must be destroyed manually after her death, completing the quest. Her defeat and the destruction of the Crucible prompts Urzael to set fire the city to continue the collection of souls.