A green witch who joins the coven out of a grave, and who turns out to be the oldest thing in the story wearing a face for the woman she loved.
Rio Vidal is the name Death uses when she is passing as a green witch, and Aubrey Plaza plays her in Agatha All Along. Wikipedia’s article on the character records that she is one of the four cosmic entities who created the Infinity Stones, alongside Eternity, Infinity and Entropy, and that her identity was never announced before the series: Plaza was cast in an unnamed role, the truth was telegraphed through the episodes, and it was not confirmed until the seventh, “Death’s Hand in Mine”. The reader who sent this list called her the green witch who is later revealed to be Lady Death, which is the shape of it.
Some time before 1750 Death, as Rio, entered a relationship with Agatha Harkness, whom she met while collecting the dead from one of Agatha’s killing sprees. When Agatha’s son Nicholas was six, Death took him, and the showrunner Jac Schaeffer has said the writers talked at length about whether Rio was his other parent before deciding it was irrelevant to the story. Agatha used the Darkhold to hide from her afterwards.
Minor spoiler
Death tracks Agatha to Westview in 2026, appears inside Wanda’s spell as an FBI agent called Rio Vidal, and tells the Salem Seven where to find her. When the coven summons a green witch to the Road, Death crawls out of Sharon Davis’s grave and walks it with them, incognito, through the second and third trials. She stays behind in the third to guide Alice to the afterlife. When Agatha helps Billy leave the Road without surrendering to her, Death confronts her in the garden in Westview; Agatha chooses to sacrifice herself, kisses her, and dies of it. Death sheds Rio’s appearance to show Billy her true form before telling him to go.
Show detailsStatues, and a rumour
The same article records that Death has been depicted in-universe before this: a stylised relief at the start of Guardians of the Galaxy, and a statue at the climax of Thor: Love and Thunder. Those are images of her, not appearances, so they are not in her list. It also records that the Russo brothers explained in 2018 why they had kept her out of Infinity War and Endgame, and that it has been rumoured she will appear again.