1. Xylitol-containing products (xylitol is an artificial sweetener often found in sugar-free candy and gum);
  2. Chocolate (although some types of chocolate are not as toxic as others, it’s safer to keep your pet away from all types of chocolate);
  3. Onions;
  4. Grapes and raisins;
  5. Fatty and fried foods;
  6. Macadamia nuts
  7. Avocados

Source

7 Foods to Avoid Feeding Your Dog or Cat
https://www.avma.org/public/PetCare/Pages/foods-to-avoid.aspx