Invisible Inkling (Invisible Inkling, 1)
The thing about Hank's new friend Inkling is, he's invisible.
No, not imaginary. Inkling is an invisible bandapat, a creature native to the Peruvian Woods of Mystery. (Or maybe it is the Ukrainian glaciers. Inkling hardly ever gets his stories straight.)
Now Inkling has found his way into Hank's apartment on his quest for squash, a bandapat favorite. But Hank has bigger problems than helping Inkling fend off maniac doggies and searching for pumpkins: Bruno Gillicut is a lunch-stealing, dirtbug caveperson and he's got to be stopped. And who better to help stand up to a bully than an invisible friend?