Hades:

• brother of Zeus

• god of the underworld

• had a helmet of invisibility 

• the Olympian brothers each received a weapon to battle the titans:  Zeus received the lightning bolt, Poseidon received the trident and Hades received the helmet of invisibility -- after they defeated the Titans they drew lots to see who would rule what -- Zeus the sky, Poseidon the seas and Hades the underworld.