The fictional character in J. K. Rowling's "Harry Potter" series Severus Snape becomes a double-agent on behalf of this secret organisation to fight Voldemort and his followers known as what?
Severus Snape: Severus Snape is a fictional character in J. K. Rowling's "Harry Potter" series. Severus Snape:  Snape becomes a double-agent on behalf of Albus Dumbledore and the Order of the Phoenix, and protects Harry throughout the series. Order of the Phoenix (fictional organisation): The Order of the Phoenix is a secret organisation in the "Harry Potter" series of fiction books written by J. K. Rowling. Order of the Phoenix (fictional organisation):  Founded by Albus Dumbledore to fight Lord Voldemort and his followers, the Death Eaters, the Order lends its name to the fifth book of the series, "Harry Potter and the Order of the Phoenix".
Death Eaters