“All the love to you, Jo,” Watson, who plays Hermione in “Harry Potter” movies, wrote in the caption of the old picture, which features herself, Rowling and fellow “Harry Potter” movie alum Evanna Lynch.
The undated picture shows Watson in a “Wonder Woman” costume, Rowling wearing a horned mask and Lynch in cat-themed makeup.
“Ahhhh I didn’t know this photo existed!!!” Lynch commented on the post.
Lynch also shared her own tribute to Rowling on Twitter: