Nemean Lion

Hercules saved the people of Nemea from the Nemean Lion by killing it. For his troubles, he received a scar from the savage beast. He kept the Lion's skin and would use it to play with his children; pretending he was a lion. ("Hercules in the Underworld").

Background[]

Slaying the Nemean Lion was the first of Heracles's Twelve Labours. He wore its dense hide as armor for most of the rest of his life, and is almost universally depicted in art wearing the skin, often with its head on his own.
Although he is never seen wearing the skin outside of its movie appearance, the fact that Herc's shirt is yellow is probably a reference to it.
The skin may have been destroyed along with Hercules's home in "The Wrong Path".