All my food is good for my animal companion, right??

Do you love avocados? Reading this post from Horse and Man started me thinking about what we feed our animal companions that are good for us but seriously and potentially detrimental to their health. Some items that come to mind are grapes, onions, chocolate, macadamia nuts, apricot/cherry/peach pits, walnuts, tomato stems/leaves, walnuts, nightshade plants, soda/alcoholic/carbonated beverages, yeast, just to name a few. What else can you add to this list?
http://horseandman.com/medical/avocados-are-poisonous-to-horses-so-is-the-tree-the-bark-the-leaves-every-part/