Elves

Inhabitants of the world long before Humans appeared, the ancient race of Elves once flourished in the forests. Slighter and shorter than humans (but still taller than the race of Dwarves), they were gifted with natural grace, speed, and considerably long lifespans. The majestic elves departed the lands of Sosaria under mysterious circumstances, not long after the fall of Exodus (as chronicled in Ultima III).

A divergent aquatic race of blue-hued Elves, known as Nixies, are first encountered in Ultima IV.

Trivia

 * After Ultima III, Elves disappeared, not only as a playable race, but from Sosaria/Britannia entirely.
 * Elves reappeared as a playable race in the Mondain's Legacy expansion for Ultima Online.
 * Elves were also scheduled to appear in the cancelled Ultima X. Their historical write-up, while extremely detailed, should probably not be considered canonical. It is viewable here.