Timmy also, but he's a "rare spawn" on a timer, I think he only shows up a few times a day and he ONLY sells one kitten each time, so if you don't make it to him in time your best bet is the Auction House. And lots of people know about him and try buying the kitten from him to resell on the AH for a considerable profit (I know it costs maybe 1g to buy it from Timmy and I have sold some on the AH for 10g each).