Like with any major film franchise, a lot of big-name actors were almost cast in the Harry Potter series, from the late, great Robin Williams for the part of Hagrid to Hugh Grant almost playing Gilderoy Lockhart. And it turns out that even JK Rowling, Harry Potter's creator, was considered for a critical part in the film franchise.
Ahead of 2001's Harry Potter and the Sorcerer’s Stone, the first film in the series, Rowling was asked to play the part of Lily Potter, Harry's mother. As you probably remember, we see Lily and James Potter in the Mirror of Erised, in a heartwarming moment where Harry gets to see his parents again.
While it would seem appropriate for the woman who gave birth to Pottermore to play the role of Harry's mom, Rowling wasn't interested. Reportedly, she did not feel she was "cut out to be an actress" and feared that "she'd mess up somehow." The role eventually went to Geraldine Somerville, who played Lily in all eight of the Harry Potter films.