Shachath(also known as the Angel of Death) is is a benevolent entity that appears to administer her kiss of death to individuals who are dying or wish for death. She is a character in Asylum portrayed by Frances Conroy.
She manifests in classic black 1940's attire. She wears a fishnet veil which covers her eyes, and when she performs the kiss of death, two large black wings spring from her back.
Shachath only appears when she is called and whomever calls receives her "kiss of death", serving much like a grim reaper. Sister Mary Eunice is agitated when she encounters the dark angel bestowing her kiss upon the Briarcliff inmate known as Miles. She has appeared before Grace, Lana Winters, Sister Jude, and Timothy Howard.
Dark Cousin - This is her first appearance. She appears to several main characters, such as Lana Winters, Sister Jude, and Grace. In the end of the episode, she gives Grace the kiss of death after she is shot by Frank in an attempt to protect Kit Walker.
The Coat Hanger - Shachath appears to Timothy Howard in the sanctuary as he is nailed to the cross. Timothy pleads for her to help him, and she replies "I'm here".
The Name Game - Shachath does not end Timothy's suffering, but believes he must cast away the Devil that possesses Sr. Mary Eunice. She later appears when Mary Eunice dies, saying she's taking both her and the Devil.
Continuum - When Briarcliff is put under the control of the state of Massachusetts and turned into a refuge for surplus inmates, Judy Martin is confronted by a domineering, unnamed new arrival who seems to bear the physical appearance of Shachath, though her voice is raspier due to cigarettes. When she attempts to usurp Judy's role of authority amongst Briarcliff's populace and sexually harasses her, Judy attacks "Shachath", only to find that the Angel was part of an elaborate hallucination she has been suffering from over the past two and a half years.
Madness Ends - Shachath appears to Jude, who is willing to accept the "kiss of death" this time around.
To Sister Jude: "I come when I'm called. That's what I do, Jude. I don't judge. I never judge."
In Ancient Hebrew, not Aramaic, "Shachat" is one of the many names for the underworld mentioned in the Old Testament, and not the name of the Angel of Death. The writing in blood on the wall that summoned Shachath was actually mispelled, and says Shachach instead of Shachath.