The Eldren are one of the many races of the Multiverse. They are beautiful and elfin, with long-boned skulls, fair skin, tapering ears, generally dark hair, and eyes which are a solid milky blue, "without orbs" (probably meaning they lack visible pupils), and shot through with silver flecks. They are said to be slender, and Erekosë said Ermizhad's brother Prince Arjavh had "a pointed golden face and slanting eyes that were milky and blue-flecked".
The Eldren were involved in a genocidal war with Humanity, where the Humans tried to exterminate all the Eldren out of extreme xenophobia. Humanity summoned Erekosë to finish off the Eldren, but he saw that the Eldren and not the Humans were the victims, and after falling in love with Ermizhad, Erekosë betrayed Humanity and slew them all to save the Eldren.
For an unexplained reason, the migration of the Eldren across the Multiverse has caused their features to alter subtly. While the same basic physical form is shared, Eldren, Melnibonéans and Vadaugh have very different eyes, with Eldren having almost blank blue eyes, Melnibonéans having generally Human/Mabden-like eyes, and Vadaugh having eyes which are purple with yellow irises, but which turn black and gold when angered.
In the novels, the Eldren are featured in the The Eternal Champion, Book One of Phoenix in Obsidian, The Dragon in the Sword, and Book Three of The Quest for Tanelorn.