Which Harry Potter companion book did J.K. Rowling publish to support Comic Relief?

J.K. Rowling published Quidditch Through the Ages to support Comic Relief.

The book first appeared in 2001 alongside Fantastic Beasts and Where to Find Them. It is presented as a Hogwarts library book written by Kennilworthy Whisp and examines the history, rules, equipment, and development of the wizarding sport of Quidditch.

The edition credited the fictional author rather than presenting Rowling as the in-world writer. Sales proceeds supported Comic Relief, the British charity known for using comedy and entertainment to raise money for social causes.

The book is sometimes confused with The Tales of Beedle the Bard, another Rowling companion volume. The latter was published in 2007 and supports different charitable work, while Quidditch Through the Ages is the companion text specifically associated with Comic Relief.