The most famous symbol of Hades is the one you cannot actually see. When the gods were fighting against the Titans, the three brothers – Zeus, Poseidon and Hades – each received special weapons made by the Cyclopes. Zeus got his thunderbolt, Poseidon the trident, and Hades received a helmet (or a cap) of invisibility. As the name implies, it made its wearer invisible to everyone, including the gods themselves (or, by some other accounts, it surrounded the wearer with a black cloud, which caused panic and terror and made everybody flee from its path).
Hades used the helmet of invisibility with success in the fight against the Titans (one of the rare occasions when he got involved in the battles that took place on the surface of the earth), but after that it seems he found no use for it, so many other characters borrowed it from him – Athena and Hermes, among others, but also mere mortals, such as Perseus. All in all, Hades seems to be rather generous with this personal belongings.
Another widely met symbol of Hades is Cerberus, the guardian dog of the underworld (initially, Hades was the name of the god as well as of the place where the dead went). The fierce creature is generally presented as a dog with three heads (but the number varies, sometimes it has 50 heads) and a snake’s tail. Its most noteworthy episode was the involvement in the twelfth labor of Hercules, when the hero had to capture Cerberus alive. In fact, Hades allowed Hercules to take the dog, as long as he brought it back unharmed.
Cerberus, symbol of Hades, is a modern representation
Other symbols of Hades include the golden keys to the realm of the dead, a golden chariot drawn by four black horses and a scepter which held the power of opening a passage between the world of the living and that of the dead. Hades also owned a herd of immortal black cattle.
As you’ve probably realized by now, the color most often associated with Hades was black, and only black animals could be sacrificed to this god. But, as god of the wealth hidden underground, gold and silver were also associated with him quite often, and all jewels.
Among the plants, symbols of Hades are the cypress, used by the ancient Greeks in funerary ceremonies, the mint, in honor of a former lover, a nymph called Minthe, and the white poplar, again for a lost lover, Leuke. All in all, though, Hades was remarkably faithful to his wife, Persephone, especially considering that she was living with her mother half of the year – and the couple is depicted together much more often than each of the two gods individually.