Book of Dogs

Once upon a time, in approximately the year 5612, an ambitious hero from a small Volkuran village declared that he would seek out every species of dog, catalogue them, and rate them according to a specially-developed scale of Good Dogness. This had been regarded as an incredibly interesting and potentially good idea by those he proposed it to, until he elaborated on what he meant by "dog": any creature that could be considered canine. And so was born the Book of Dogs.
This included monstrosities such as hellhounds, cerberi, and various forms of dog-shaped demon. Less terrifyingly, it included the more canine forms of agathions. And it should be noted that the fey, too, have many dog-like species that Jeremy Dýralæknir was insistent on including in this work of his. But first came the study of the native dogs of the Material Plane: from the common homeless pups running around Volkur's streets to the fearsome wolves lurking within the thick forests of Yksinka.

Tried to pet a Cerberus. Made the other two heads angry. Lost me arm. Worth it.

— Jeremy Dýralæknir

Dýralæknir was not able to manage such a task on his own, of course, and had to recruit the aid of many curious adventurers who wished to see this boneheaded plan through. Reports say that his list numbered somewhere in the hundreds before his mysterious disappearance into a rift of reality - now, years later, his exploits are tracked by a self-updating book located in the capital of Volkur under heavy guard. Whilst it would absolutely be possible to locate the author using it, previous attempts have been rebuffed with the frank explanation that he's working and would like to not be distracted until his task is done.