structural:summarization, structural:expansion
In the Roman period

As early as the 4th century BC, Romans had adopted Hermes into their own religion, combining his attributes and worship with the earlier Etruscan god Turms under the name Mercury. According to St. Augustin, the Latin name "Mercury" may be a title derived from " medio currens ", in reference to Hermes' role as a mediator and messenger who moves between worlds. Mercury became one of the most popular Roman gods, as attested by the numerous shrines and depictions in artwork found in Pompeii. In art, the Roman Mercury continued the style of depictions found in earlier representations of both Hermes and Turms, a young, beardless god with winged shoes and/or hat, carrying the caduceus. His role as a god of boundaries, a messenger, and a psychopomp also remained unchanged following his adoption into the Roman religion (these attributes were also similar to those in the Etruscan's worship of Turms).

The Romans identified the Germanic god Odin with Mercury, and there is evidence that Germanic peoples who had contact with Roman culture also accepted this identification. Odin and Mercury/Hermes share several attributes in common. For example, both are depicted carrying a staff and wearing a wide-brimmed hat, and both are travelers or wanderers. However, the reasons for this interpretation appear to go beyond superficial similarities: Both gods are connected to the dead (Mercury as psychopomp and Odin as lord of the dead in Valhalla), both were connected to eloquent speech, and both were associated with secret knowledge. The identification of Odin as Mercury was probably also influenced by a previous association of a more Odin-like Celtic god as the "Celtic Mercurius".

A further Roman Imperial-era syncretism came in the form of Hermanubis, the result of the identification of Hermes with the Egyptian god of the dead, Anubis. Hermes and Anubis were both psychopomps the primary attribute leading to their conflation as the same god. Hermanubis depicted with a human body and a jackal head, holding the caduceus. In addition to his function of guiding souls to the afterlife, Hermanubis represented the Egyptian priesthood the investigation of truth.

Beginning around the turn of the 1st century AD, a process began by which, in certain traditions Hermes became euhemerised – that is, interpreted as a historical, mortal figure who had become divine or elevated to godlike status in legend. Numerous books of wisdom and magic (including astrology, theosophy, and alchemy) were attributed to this "historical" Hermes, usually identified in his Alexandrian form of Hermes Trismegistus. As a collection, these works are referred to as the Hermetica.