". . . a Slytherin girl who reminded Harry of a picture he’d seen in Holidays with Hags."
-- Harry's opinion (CS11)
“Urgh — essence of Millicent Bulstrode . . . Bet it tastes disgusting.”
-- Ron Weasley, as Hermione started to drink Polyjuice Potion (CS12)
Slytherin, 1991 – 1998 (PS7)
Member of Umbridge’s Inquisitorial Squad in her fifth year (OP32). In her second year, Millicent partnered Hermione at the Duelling Club at Snape’s direction, resorting to a headlock despite the standard “no contact” rule of wizard duelling, leaving some black hair on Hermione’s robes in the process … which the quick-witted Hermione saved for use in her Polyjuice Potion. Unfortunately, the hair was not Millicent’s own; apparently she keeps a cat (CS11, CS12).
An “M. Bulstrode” checked out Quidditch Through the Ages (6 February) (QA).
Black-haired (or Hermione wouldn’t have made her mistake), with a square build and heavy jaw, Millicent was “no pixie” in her second year (referring to her size and build); by their fifth year she was still able to physically overpower Hermione. Both Ron and Harry consider Millicent ugly; she reminds Harry in particular of a hag (CS11, OP32).
Other canon notes and references
In 2001 Rowling flashed a notebook during a BBC interview that showed her notes on the students in Harry Potter's year and Millicent is noted as being a Half-blood. However, Millicent's ancestry cannot be considered canon without confirmation from Rowling, because the notebook conflicts in too many places with the stories as they were actually published (HPM).
Played in the movies by Helen Stuart IMDB