In Greek mythology, Mentor was the son of Heracles and Asopis. In his old age Mentor was a friend of Odysseus, who had placed Mentor and Odysseus' foster-brother Eumaeus in charge of his son Telemachus, and of Odysseus' palace, when Odysseus left for the Trojan War.
When Athena visited Telemachus she took the disguise of Mentor to hide herself from the suitors of Telemachus's mother Penelope. As Mentor, the goddess encouraged Telemachus to stand up against the suitors and go abroad to find out what happened to his father. When Odysseus returned to Ithaca, Athena appeared briefly in the form of Mentor again at Odysseus' palace.
Because of Mentor's relationship with Telemachus, and the disguised Athena's encouragement and practical plans for dealing with personal dilemmas, the personal name Mentor has been adopted in English as a term meaning someone who imparts wisdom to and shares knowledge with a less experienced colleague.
The first recorded modern usage of the term can be traced to a 1699 book entitled Les Aventures de Télémaque, by the French writer François Fénelon. In the book the lead character is that of Mentor. This book was very popular during the 18th century and the modern application of the term can be traced to this publication.

from the internet