Animals
List incomplete, more probably coming soon.
Glaucus atlanticus
(common names include the blue sea dragon, sea swallow, blue angel, blue glaucus, dragon slug, blue dragon, blue sea slug, and blue ocean slug)
Sea slugs in general are all incredibly beautiful creatures to behold, but this one is my favorite.
Fairy-bluebird
It's creatures like this that make me understand where so much of mythology's beings came from, because creatures like this make me wonder about how the first humans to meet them would have reacted to their existence!
Bloody Belly Comb Jelly
I love it when living beings are just weird as shit for no reason.
Bargibant's seahorse
Probably my favorite example of camoflauge.