Harry Potter's Great British Thespians

Imelda Staunton as Dolores Umbridge, 5, 7
Pink and perky, and with her office walls covered with moving pictures of cats, Dolores Umbridge at first seems another harmless eccentric as the fifth book's Defense Against the Dark Arts teacher. Soon, though, she's the students' nightmare: a stealthy Stalinist with a smile like a rictus. It's a delightfully seditious role for which Staunton, 54, was well suited. London-born, of Irish parentage, she's barely five feet tall and would escape the notice of most casting directors. That's her gift: disappearing into any role she inhabits. She won raves, and an Oscar nomination, as the cheerful abortionist in Mike Leigh's Vera Drake, and will work with Leigh in his next film.

• Growing Up with Harry Potter