Memory Charm

"If there's one thing I pride myself on, it's my Memory Charms."

- Gilderoy Lockhart

A Memory Charm is a spell used to erase some or all memories from an individual's mind. The incantation for this charm is Obliviate. It is different from the charm that creates false memories.

Effects
Memory Charms are generally intended to erase a specific memory. They are regularly used if a Muggle witnesses something related to the wizarding world; the Ministry of Magic has Obliviators remove their memories of the event, such as if a Muggle sees a dragon. Occasionally, a mass use of Memory Charms is necessary to cover up major incidents that violate the Statute of Secrecy, such as the Ilfracombe Incident. Some Muggles often slip through the cracks in these situations, according to Blenheim Stalk in Muggles Who Notice.

However, if performed improperly, a Memory Charm can erase significant portions of an individual's memory and cause brain damage. For instance, Gilderoy Lockhart attempted to wipe the memories of Harry Potter and Ron Weasley during the events surrounding the re-opening of the Chamber of Secrets. However, Ron's damaged wand backfired, and caused Lockhart to suffer extreme amnesia. He is currently a resident in the Permanent Ward of St Mungo's.

Also, Barty Crouch Sr. placed a Memory Charm on Bertha Jorkins to try to make her forget her discovery that he was keeping his son in captivity. Because he was a powerful but untrained wizard, the charm damaged her memory permenantly.

Breaking the Charm
Memory Charms can be broken through torture. In 1994, Lord Voldemort and Peter Pettigrew broke a Memory Charm placed by Barty Crouch Sr on Bertha Jorkins, and extracted information from her regarding the whereabouts of Crouch's son.

In 1997, Voldemort had Antonin Dolohov and Thorfinn Rowle tortured with the Cruciatus Curse after they failed to capture Harry Potter. Hermione Granger had cast Memory Charms on them so as to cover the trio's tracks, and it appears that the charms were not broken by torture, since the Death Eaters remained unaware that Ron Weasley was with Harry and Hermione, rather than sick at home with spattergroit as had been claimed, for months afterwards.

Etymology
The incantation "obliviate" may be derived from the Latin oblivisci, meaning "forget".

Behind the scenes

 * In Chapter 9 of Deathly Hallows, just prior to erasing Antonin Dolohov and Thorfinn Rowle's memories, Hermione says that she has never performed a Memory Charm before, despite having already altered her parents' memories . However, J.K. Rowling has said this was a different charm, which alters memories rather than removes them.
 * In the W.O.M.B.A.T.'s in J. K. Rowling's Official Website they are named by Forgetfulness Charms.