The term is originally derived from Archimago an antagonist in the epic poem The Faerie Queene. The variant spelling "archimage" occasionally appears in the poem, and this alternate spelling was later used by poet Percy Bysshe Shelley as a synonym for wizard. Shelley's use in turn led to Ursula K. Le Guin coining the term modern spelling and connotations of the term when she used "archmage" to describe the head of a magical school in her novel A Wizard of Earthsea (with the archmage's pupils dubbed "mages"). The term has since been commonly used in fantasy literature and media to refer to an exceptionally skilled mage.
See Special:Whatlinkshere/Etymology:Archmage for a list of articles using this term.