Is series of unfortunate events a fiction book?

Yes, "A Series of Unfortunate Events" is a fiction book series written by Lemony Snicket (the pen name of Daniel Handler).

The series tells the story of the three Baudelaire orphans, Violet, Klaus, and Sunny, who are constantly pursued by the villainous Count Olaf, who wants to steal their inheritance. The books are characterized by their dark humor, witty dialogue, and macabre situations.