One of the 3 'Unforgivable Curses' in Harry Potter by J.K. Rowling.
The Imperious Curse is used to take full control of the body of another. As with Avada Kedavra use of this curse will have you placed in the Wizard Prison 'Azkaban'
"You will do exactly as I wish....IMPERIO!", The young wizards eyes glazed over and he seemed a million miles away, yet aware of the need to follow and external force.