Tommy Taylor and the Bogus Identity (2010)
Author: Mike Carey | Illustrator: Peter Gross | Page Count: 144
"But the unpalatable fact is that you auditioned to play yourself and didn't get the part."
The Tommy Taylor™ books are a cultural phenomenon. Tommy is a boy wizard with a small group of friends, whose adventures have spanned thirteen books. The collective routinely save their world from the kind of villains that typically populate children's literature.
The author of the books is Wilson Taylor. It's a well-known fact that Wilson based the lead character on his own son, Tom Taylor. Consequently, Tom has grown up in the public eye. He's not a writer and had no direct input in the books, but people love him, regardless.
He attends conventions and answers questions from fans, some of whom can't separate reality from fiction.
If you're thinking along the lines of Harry Potter crossed with Christopher Robin, then you're on the right track.
But that's merely a stepping stone into a much larger ocean of unpredictability. (FTR, I've not read the Potter books; my only experience of the character is the first film and half of the second one, so I'm basing my comparison on that.)