Werecats are creatures mentioned in passing of the Witcher series. It is possible that they are similar to bobołaks, but not certain. Presumably the "were" portion of the name alludes to some transformative physical power, like werewolves but resulting in a large cat-like creature.
The Witcher: Reason of State
They also appear in the Witcher comic "Racja stanu".
Gallery
Werecats in comics.
Werecat in Gra Wyobraźni