The Last Unicorn by Peter S. Beagle

The unicorn had lived since before memory in a forest where death could touch nothing. Maidens who caught a glimpse of her glory were blessed by enchantment they would never forget. But outside her wondrous realm, dark whispers and rumors carried a message she could not ignore: "Unicorns are gone from the world." Aided by a bumbling magician and an indomitable spinster, she set out to learn the truth.

Cover art by Gervasio Gallardo.

Ballantine Adult Fantasy 1972 paperback, fourth printing in okay condition, see photos. Personal inscription on inner page.