Animagus

In the Harry Potter universe, an animagus is a wizard capable of changing into an animal. Several animagi have been mentioned in the Harry Potter books, most famously Professor McGonagall, who is depicted right in the first chapter of the first book as being able to change into a cat.

Warning: Wikipedia contains spoilers[?]

Offically, all animagi have to register themselves with the Ministry of Magic[?], as transforming into an animal can be extremely dangerous. However, several unauthorised animagi have been mentioned in the series. These include:

• James Potter[?] (into an antelope)
• Sirius Black (into a large dog)
• Peter Pettigrew[?] (into a rat)
• Rita Skeeter[?] (into a beetle)