List of fictional alien species: Y

Name Source Type
Y5 Adventure Time: Distant Lands Rabbit-like humanoid
Yacatisma Church of the SubGenius
Yag-Kosha Robert E. Howard's The Tower of the Elephant Humanoid elephant
Yaetuans Christan Clines's The Yaetuan Sagas Six limbed intelligent species
Yanme'e Halo
Yautja Predator Humanoid. Also known as Predators. They are a warrior race that hunts down other sentient races for sport, but follow a code of honor and deeply respect those who manage to defeat one of their own in combat.
Yariru Vampire Idol Vampire-humanoids
Yazirian Star Frontiers Ape-like humanoid glider
Yeerks K. A. Applegate's Animorphs Slug-like parasites. They need a host to see, walk, and communicate, and are the main antagonists of the Animorphs series, intent on enslaving other species.
Yehat Star Control Pterodactyl-like
Yeti Doctor Who
Yilane West of Eden series by Harry Harrison
Yip-Yips Sesame Street
Yliis 2300 AD
Yolkians Jimmy Neutron Gooey Slug-like aliens with egg shaped suits.
Yomingans Schlock Mercenary
Yor Galactic Civilizations
Yorn Star Control 3
Ythrian Poul Anderson's Technic History Eagle-like aliens
Yridian Star Trek
Yugopotamians The Fairly OddParents Squid-like aliens with dome-covered brains.
Yuuzhan Vong Star Wars Humanoid