This might be a cop-out since it is technically not one creature, but it was simply too difficult to narrow it down. Myths and fantasy have brought to life creatures of all varieties: minotaurs (human/bull), satyrs (human/goat), harpies (human/bird), naga (human/snake), pegasus (bird/horse), chimera (lion/goat/snake), wolpertinger (rabbit/deer/bird), and many more. I have always been partial to those that fly (see dragons above), so the hippogriff (eagle/horse) holds a special place in my heart. While it first came to my attention through Dungeons & Dragons, Harry Potter and the Prisoner of Azkaban‘s Buckbeak is the most prominent.