Elves

The elves who have settled upon De'Ru are similar, but not identical, to your basic AD&D elves.  There are some slight differences. They are referred to as elves by the Terrans, a title that has been adopted by other races as well, because of the resemblance they bear to these people. They call themselves the Sidhe, of course.

Description:  As previously mentioned, the "elves" on De'Ru are very similar to those found in most other campaign settings.  They tend to be taller, averaging between 5 and 6 feet, and sometimes even upwards of that.  They are slender, muscular, and beautiful, their angular features near perfection.  Their ears are longer than a human's, and pointed, their eyes almond shaped, their eyebrows slender and upswept.   Their fingers are slender and long, able to perform intricate tasks.
The skintone of elves tends to lean toward pale, though hair and eye color vary widely.

Skills and Abilities:  Elves are skilled at woodland lore, excellent at ranger tasks.  They can move silently, slipping unheard and unseen through the forests of their home.  They can leap lightly and almost effortlessly from rock to rock or branch to branch.  Their hearing is excellent, as is their nightvision, and even their sense of smell is exemplary. 
Their bowmanship is legendary, their weaponsmithing and craftmanship as well.  Elvenmade items fetch a hefty price on the open markets on De'Ru, known to be of exceptional quality by all races.
Of all races upon De'Ru, except perhaps the dragons, the elves are the most adept at the magical arts, having perfected their skills millenia before ever setting foot upon this world.

Ecology:  The elves much prefer the wilds to the "civilized" world, making their homes in deep forest glades, where they have perfected the art of moulding the trees and the earth to their liking, making their homes out of the very living world around them.   Nature is of the utmost importance to the elves, and they do not look kindly upon poachers and polluters.  They understand that it is necessary for some of the more crude races to fell trees and clear land to build, as they do not possess the skills that the elves have had so long to perfect, but needless waste and destruction near elven lands will be met with violence.
Elves live for centuries, sometimes even a millenia or more, and are not considered adults until around 120 years of age.  Children are born one at a time, though twins occur about as often in elves as they do in humans.

Society:  Elven cities are vast, their homes and beautiful gardens spread out over whole forests, melding into the woods like they had always been there.  There are definite castes within elven society, their people being led by a council of nobles and protected by a warrior caste.
Other sylvan folk are commonly found in elven cities, being on excellent terms with the elves.  Humans are rarely found within the elven cities, as elves do not believe that most humans could truly appreciate the beauty that is an elven city.  Ferrea are permitted more freely, simply because of their animal nature, which the elves seem to think puts them closer to nature.  Any dark races found within elven lands are spies, prisoners, or suicidal.

Religion:  All De'Ru gods are recognized by the Sidhe, but the most revered are Dalista, Hylishilva, the four deities of the elements, Alledryn, and Dauneth. 

Special Notes:  The Sidhe get along well with all other Sylvan races, and magical creatures (at least good or neutral ones).  Humans are considered friends to the elves, even if rarely found within their cities.