Trismegistus. While there are many different sources providing information about him, there are still many who doubt he ever existed. Personally, I believe that an alchemist named Hermes might have actually existed at some point, even though his deed are most likely exaggerated.
In my opinion, Hermes Trismegistus is not one person, but, in fact, many who assumed the name over the centuries. Probably, there was a well-known and successful alchemist, who most likely lived around the time of Moses as this was the earliest mention of him.
As his fame rose, probably him and/or his followers might have started associating his name with the God Thoth, giving him a god-like