Nemean Lion

Family

 According to Greek mythology, the Nemean Lion was one of the many offsprings born to Typhon and Echidna. Its siblings include Cerberus, Chimera, the Eagle (who ate Prometheus' liver), the Gorgon, the Harpies,  the Hydra, Ladon (the Dragon of the Hesperides), Orthus (the watch-dog of Geryon), Scylla, the Sow, and the Sphinx. 

The genealogy posted in Marvel's "Mystic Arcana" confirms some of these relationships. But gives the Lion an ancestry that goes beyond the Greek legends. Its paternal grandparents are Tartarus and Gaea, its maternal grandparents are Phorcys and Ceto. Phorcys, a minor figure of Greek legend, is identified here as one of the children of Set the Elder God. Making the Lion related to the various Elder Gods and their numerous descendants. 

Tale

The Lion was supposedly nurtured by either Selene, the Moon Goddess or Hera, Queen of the Gods. They raised it to adulthood and then set it loose " among the hills of Nemea, to be a plague to mankind" (Hesiod). Nemea was an area of the  northeastern Peloponnese. The Lion supposedly claimed much of the surrounding area for its own. Preying on human and animals alike. It could not be killed due to its invulnerable skin, which could not be harmed by arrows or swords. 

When Eurystheus, King of Mycenae assigned impossible tasks to his cousin Hercules, slaying the Lion was the first one. Hercules tried and failed to kill it with conventional weapons. But then used a wooden club to daze it. Before approaching it from behind and grabbing it with his bare arms. Based on the version, Hercules either strangulated the animal or broke its neck. He returned to Mycenae carrying the giant corpse on his shoulders. Eurystheus was terrified and forbid Hercules from ever entering the city again. 

Hercules supposedly skinned the dead Lion. Using the invulnerable skin as armor in subsequent adventures.