Sister Blackbeak was a shryke who worked for Lentil Spume in the Phrax Glade. She wore a cloak stitched together from pieces of the robes of the Guardians of Night. Sister Blackbeak acted as the commander of the Phrax Glade Death-Cheaters. She was killed by Rook during the Battle of the Phrax Glade. She was mentioned in The Lost Barkscrolls.