White Box In Boots is a short, but brilliant pay what you want class by James M. Spahn.
This class doesn't let you play a man-sized humanoid cat or something like that. It literally allows you to play as Puss in Boots. The class is referred to as the Master Cat and it's a five level class that allows you to play a house cat that's able to walk upright, talk, and do all the fun swashbuckling stuff.
The class has some really nice abilities. They can't (or rather won't) wear armor but their AC bonus against man-sized (and I assume larger) opponents is phenomenal and their bonus against halfing and goblin-sized foes isn't too shabby. They are also expert climbers, are hard to surprise, always land on their feet, gain some saving throw bonuses, and are quite charming. They receive all of these things at first level and some improve as they level.
While it wouldn't be great for a serious game, this is a well designed little class for Swords & Wizardry White Box.