Cats can eat olives, but only in very small amounts and if the olives are plain, unsalted, and unseasoned. Olives are safe for cats to consume occasionally but they are high in sodium, which can cause stomach upset, vomiting, diarrhea, or even sodium poisoning in larger amounts. Additionally, olives with pits pose a choking hazard, and many commercial olives contain preservatives or are soaked in salty brine, which can be harmful to cats. While olives contain some vitamins and antioxidants, they do not provide significant nutritional benefits to cats and are considered empty calories. Overall, feeding cats a tiny amount of plain olive occasionally is generally safe, but they should not be a regular part of the diet, and caution is needed especially with cats that have kidney or heart issues.