One of our cats HATES when my wife isn't wearing enough clothing. I can walk around fully nude no problems. My wife wears short shorts and he will get visibly upset and start attacking her until I come defend her. If she puts on pants he goes right back to normal. Doesn't attack people and is generally pretty chill otherwise. Our cat has the political leanings of the Taliban apparently.
My former roommate's dog hated hats. He rarely barked at anything but if someone walked in the apartment wearing a hat he would flip the fuck out and bark at them until they took it off.
I got a full body werewolf costume for Halloween when I was a kid, and thought it would be funny to scare our dog. So I hid behind a door and when he walked in, I jumped out and roared at him. It wasn't well thought out. He was half a second away from biting my face off. Thankfully I recognized the danger and ripped the mask off. He did not get scared. He was ready to murder. At least we knew he'd protect us from a werewolf after that.