This is Trogdor the Burninator, aka Troggie. He happens to be the silliest cat in the world. This is where we find him at least once everyday. Notice that he is about 4 times too wide for the tray he is sitting in. That's the nature try, by the way. However, it happens to be conveniently located on the Spike's cage, so Troggie sits in it in hopes of a snack (which will only make the tray fit even less, but he doesn't seem to care).
Spike does not care for this arrangement. If you could hear this picture, you would know what it means to listen to a completely pissed off guinea pig. He was running around his cage squealing in rage and a little bit of panic and Troggie thought that he was being quite ridiculous. I believe (judging from Troggie's body language) that he is telling the guiea pig to just hold still and it will all be over soon.
I think this picture best conveys how ridiculous this cat is. Not only is he way too big for the tray, he is seriously warping the cage! We've been talking about this and trying to come to a resolution, but we're not getting very far. Troggie only has one demand and as much as Saragh loves him, she just won't consent to letting him eat her guinea pig. They appear to be at an impasse, but Spike is thinking of listing himself on craigslist with the specification that he go to a nice cat-free home.