Arthur Spiderwick is a fictional character from the children's book series titled "The Spiderwick Chronicles," created by Tony DiTerlizzi and Holly Black. He is a naturalist and the author of the "Field Guide to the Fantastical World Around You," which details various magical creatures and their habitats. The series follows the adventures of the Grace children, who discover Arthur's guide and encounter the fantastical beings he describes. The books blend fantasy and adventure, captivating young readers with themes of curiosity and exploration in a hidden magical world.