Today marks 20 years since Professor Lupin taught Harry how to produce a full-fledged Patronus in Harry Potter and the Prisoner of Azkaban. To celebrate, Bloomsbury — the home of Harry Potter books in the UK — gathered 26 children’s book artists to draw their own interpretations of a Patronus for a campaign called “Patronus on a Postcard.” 

Potterheads can purchase the illustrations in an auction to raise money for the charity BookTrust, a program that helps kids across the UK develop a love for reading.

Check out some of our favorite Patronuses, including Neal Layton’s hedgehog, pictured above.

Patronus on a Postcard Steven Lenton

“Mole” by Steven Lenton

Patronus on a Postcard James Mayhew

“Husky” by James Mayhew

Patronus on a Postcard Emily Gravett

“Otter” by Emily Gravett

Patronus on a Postcard Levi Pinfold

“Doe” by Levi Pinfold

Bidding will be held from July 8-18 here.

Photos: Patronus on a Postcard