People foods?

Are there any foods that are extremely bad for cats? I know a diet based off people food is bad, but what about for occasional treats? Chocolate can make dogs sick or even kill them, is that the same for cats? My cats just looovvve to get in to my food! I cant keep them away So I just want to make sure that if I share a tiny bit it wont hurt them.
Thanks

Onions are really bad for cats, even in small doses.

Thank you very much! Im relieved to see cheese is not on there, they both got a little bit last night. Little piggies

I give Zoey just a small small nibble of cheese occasionally.. otherwise its like milk, you shouldnt give it to them all the time.

Chococlate is really bad for cats, it could make them really sick. Onions are also bad and I think garlic is too. Beware of these food.