Will Blake is the main antagonist of the fourteenth Goosebumps book, The Werewolf of Fever Swamp, and the tertiary antagonist of the Goosebumps film.
Grady Tucker first met Will after Grady's family moved into their new home in Florida. The boys quickly became friends. When Grady met Cassie later on, he learned of werewolves and one most likely existing in Fever Swamp not too far from his house, due to animal killings and a hunter gone missing. Will did not believe in such things and often argued with Cassie that werewolves are not real. As days went by, Grady eventually ventured into the swamp alone with Will. When Will vanished a few minutes after Grady entered the swamp he started looking for him. Then Grady was attacked and bit by the werewolf who he realizes from the facial features is Will. Luckily for Grady before he passed out, Grady's dog Wolf attacked Will and fought him off. After The Swamp Hermit witnessed their fight, he brought Grady home where his father told him what the Swamp Hermit witnessed. Grady had his dad check Will's house, only to find the house mangled and no one living there. After that night, Grady soon learned that Will cursed him when he bit him. With Will gone, he has the swamp all for himself and now goes with Wolf on hunts and explorations in Fever Swamp during full moon nights.
The TV show version of Will's character is slightly different from his book counterpart. In the TV episode, he believes in werewolves and accuses the swamp hermit of being one as opposed to the novella where he scoffed at Cassie's beliefs in them. It is also stated that he killed the Swamp Hermit's wife and children (which was never stated nor implied in the original novella). Grady ran into the Swamp Hermit when his net caught what was the werewolf when he actually caught a deer. The Swamp Hermit is then attacked and killed by the werewolf. When the full moon is obscured by clouds, Will partially reverts back to human form. Having become a friend to Grady, Will warns him to leave before he becomes uncontrollable again. But the moon becomes visible again and Will begins compulsively howling as he turns back into a savage beast. As Will attacks Grady, Wolf showed up to defend Grady. Wolf knocked Will into the quicksand-acting bog of Fever Swamp and he sank to the bottom. What appeared to be his skeleton rises from the swamp the next night.
in the Goosebumps film, Will Blake's werewolf form appears in an abandoned Supermarket rummaging through the meat aisle until Champ accidentally alerts him of the groups presence. By opening a soda he pursues them throughout the Supermarket into a parking lot, only to be rammed by Lorraine's car sent flying into a dumpster. He reappears outside Madison High School with the other monsters as Slappy the Dummy leads them into attacking Madison High School to dispose of R.L Stine. He was about to attack Taylor, but is saved when Champ bites him with his "silver teeth filings" The werewolf appears again with the other monsters pursuing a bus Stine and and the kids are using to escape only for it to be revealed to be a decoy rigged to explode when the werewolf and the Abominable Snowman open it's doors. He is sucked back into a book that R.L. Stine and Zach wrote by the final battle.
In his concept art, he has a bigger snout and doesn't have his tattoo . He is also has more fur and in lighter gray. In the Supermarket scene, there were supposed to be four werewolves instead of just him.