Marietta Edgecombe

Marietta Edgecombe is a student at Hogwarts School of Witchcraft and Wizardry. She was sorted into Ravenclaw House and is a friend of Cho Chang, the Seeker for their House Team.

In Order of the Phoenix, Marietta accompanied Cho in joining Dumbledore's Army, despite her obvious suspicion of Harry Potter's intentions as well as his claims that Voldemort was still alive.

Due to pressure from her mother, who worked at the Ministry of Magic, and Dolores Umbridge, Marietta betrayed the D.A. to the Ministry. She would, however, come to regret this when her face broke out so severely, that she took to obscurring her face.

So that she could not incriminate Dumbledore and Harry, just before she was to confess all, Kingsley Shacklebolt, an Auror and a member of the Order of the Phoenix, obliviated her memory.