The H.I.V.E. Headmistress is the teacher of the H.I.V.E. Academy. Her only role is, "Final Exam" where she hired Gizmo, Jinx and Mammoth to defeat the Teen Titans. However they failed, and the headmistress promised they will be "strictly diciplined".
The H.I.V.E. Headmistress also appeared as cameos in "The Lost Episode" as a citizen, and where she participated in the Brotherhood of Evil along with other several villains from the past. She was flash-frozen along with the other villains.