Vampire deer.

I’d heard of musk deer but had no idea that they had tusks and no antlers, nor that they weren’t actually deer. They’re apparently the only living member of their taxonomic family, and more closely-related to bovidae (eg antelope, goats, cattle, bison) than cervidae (eg deer, elk, moose, caribou).

I also just learned that there is a species of true deer (cervidae) with tusks — the water deer, native to China and Korea.

Edit: caribou are also called reindeer outside of North America. I didn’t know that reindeer are real and are just caribou until I saw a clip of someone on Would I Lie to You being made fun of for thinking they weren’t real. They’re only called reindeer in the context of Santa’s reindeer, here.

Tame Impala Deer