Someone or something that provides a great benefit, has done very good work, has performed some heroic deed or function, etc., but has not received the credit or recognition they deserve. It's the volunteers who are the real unsung heroes of this event. They're the ones who put in countless hours without pay to ensure that everything runs smoothly from beginning to end. The company is known for their expensive smart devices, but its their subscription-based cloud storage that has been their real unsung hero, responsible for over 45% of their annual profit for the last four years.
Fig. a hero who has gotten no praise or recognition. The time has come to recognize all the unsung heroes of the battle for low-cost housing.
Individuals not famous or celebrated as they deserve to be. Unsung alludes to the long epic poems of Homer and Virgil, which celebrated the heroes of Greece and Troy. Indeed, a version of the term, which dates from the late seventeenth century, appears in Alexander Pope’s translation of Homer’s Iliad—“Unwept, unhonour’d, uninterrid he lies!”—words picked up a century later by Sir Walter Scott in one of his most famous poems, “The Lay of the Last Minstrel” (1805): “And, doubly dying, shall go down To the vile dust, from whence he sprung, Unwept, unhonour’d, and unsung.”