The Harry Potter Illustrated Collection refers to a set of books that feature the original Harry Potter series written by J.K. Rowling, with illustrations by Jim Kay. There were three books released in the series:

1. “Harry Potter and the Philosopher’s Stone” (or “Harry Potter and the Sorcerer’s Stone” in the United States): This book was originally published in 1997 and introduces readers to the magical world of Harry Potter. The illustrated edition, featuring artwork by Jim Kay, was first published in 2015.
2. “Harry Potter and the Chamber of Secrets“: The second book in the series was first published in 1998, and its illustrated edition followed in 2016. It continues Harry’s adventures at Hogwarts School of Witchcraft and Wizardry.
3. “Harry Potter and the Prisoner of Azkaban“: The third book was published in 1999, and its illustrated edition was released in 2017. In this installment, Harry learns about Sirius Black, a dangerous wizard who has escaped from the wizarding prison of Azkaban.