In Homer's Odyssey, Mentor son of Alcimus is the aged Ithacan friend to whom Odysseus, leaving for Troy, entrusted his household and son Telemachus. Athena repeatedly assumes Mentor's form and voice to guide Telemachus and later to aid Odysseus. His name entered modern languages as the word for a trusted adviser, chiefly via Fénelon's Les Aventures de Télémaque (1699). Distinct from other Mentors and from Athena's earlier guise as Mentes.
Adapted from Wikipedia, "Mentor (Odyssey)" · CC BY-SA 4.0
I.Guardian and Athena's mask
Homer introduces Mentor as Odysseus's comrade left in charge of the palace when the king sailed. At the Ithacan assembly he alone rebukes the people for suffering the suitors. Athena then borrows his likeness beside Telemachus on the voyage to Pylos and Sparta, again in the hall-fight, and at the final peace — so that much of what readers remember as "Mentor's counsel" is the goddess speaking through his shape.
Athena's appearance as Mentor must not be confused with her earlier disguise as Mentes in Odyssey book 1. The atlas also keeps mentor-ithaca apart from other figures named Mentor (for example among Eurystheus's attendants or Trojans).
II.Word and legacy
Latin and modern European languages adopted Mentor as a term for one who imparts wisdom to a less-experienced colleague. The first clear modern usage is traced to François Fénelon's 1699 Télémaque, whose Mentor became the model for the pedagogical sense of the word.