Unicorns

Unicorns, beings of magic. They basically look like a horse with a big horn on the forehead. Unicorns are intelligent, but really unhappy with their existence. Because after disappointing a wizard, he cursed them. They were forced to kill all their females, and any kind of sexual energy now horrifies them. This is of course, why they are used to test, if someone is still a virgin...

Where they can be found is unknown.

The Avatar meets only one Unicorn, more below.

Lore
''Fanciful stories of these creatures abound in rural areas. The unicorn appears as a splendid, young, white stallion with a single great horn rising from its head. Legends tell of how only those who are truly virtuous may approach a unicorn. Unicorn sightings are rare - so rare in fact that most serious scholars deny their existence.''

- from "Fellowship", Ultima VII 

Notable examples

 * The Avatar meets Lasher the Unicorn in Dungeon Destard in Ultima VII. Lasher tells the whole story of the Unicorns, but only if the Avatar is still a virgin. Because if he or she screws around (namely in the House of Baths), Lasher is so disgusted, he avoids the Avatar like the plague.