The Chimer (literally, the People of the North), also called the Changed Folk, Velothi, or Changed Ones, were the Aldmeri tribes of dissidents who abandoned the ways of Summerset Isle and embarked on a great exodus to Morrowind. They followed the prophet Veloth, who spoke to them on behalf of Boethiah, Prince of Plots, and two other "Good Daedra". The teachings of Veloth and the Daedra spawned a new culture on Tamriel and a new people, sparking the period of the High Velothi culture. They were dynamic, ambitious, long-lived Elven clans devoted to fundamentalist ancestor worship. They appeared like other elves, but their skin was a darker shade of pale gold than the Altmer. Almalexia of the Tribunal apparently maintained her appearance as a Chimer (as did Vivec, partially) despite the Curse which changed the Chimer into the Dunmer.
For more information, see the main lore article.