Roman god of communication, messenger of the gods
Known to the Greeks as Hermes, Mercury was the son of Jupiter and Maia. Worshipped by the Romans from early days (many of the legends of Hermes were 'adopted' from Greece), a temple was dedicated to him on the Aventine Hill in Rome on 15th May, 495 BC, the anniversary of which was celebrated annually, jointly with his mother.
As the Greeks, so with the Romans. He was a god of trickery, deceit and thievery, also of commerce and communication - a strange mix, which made me wonder about the honesty of Roman businesspeople. He was considered to be the messenger of the gods, and is also said to have guided the souls of the dead into Hades, taking the role of a psychopomp.
His role as thief began shortly after his birth, when he stole a herd of cows from Apollo, tricking his pursuers by making shoes for the cows and having them walk backwards to confuse the trail. From the entrails of some of the cows, Mercury made the strings of a lyre, which he later traded with Apollo for the cows he had stolen.
Fleet of foot, he is often pictured wearing either winged sandals (talaria) or a winged cap (a petasus), and he is frequently portrayed carrying a caduceus, a staff of hazel (or willow) entwined with snakes, which served to protect him in his travels. His 'job' as messenger enabled him to move throughout all the worlds, both celestial and earthly, which enabled him to become knowledgeable about many things which were mysteries even to other gods.
He later became identified with the Germanic god Woden (Norse Odin), and indeed, the same weekday was dedicated to him - Wednesday ("Wodin's day") and the Norwegian Onsdag (Odin's Day), also known to the Romans as Dies Mercurii ("Mercury's day") - a reminder of this is still with us, the French for Wednesday being Mercredi.
He was known by many names in different cultures. Hermes, Wodin, Turms to the Etruscans, Thoth to the Egyptians, Nabu to the Assyrians and Gud to the Sumerians.