Is Thranduil a Sindar elf, a Silvan elf or a Wood-elf, and what is the difference, if any?
Thranduil was most certainly not a Wood-elf. Silvan elf is just another term for Wood-elf. (Silvan Elves were divided into two groups, the Galadhrim of Lothlorien and the Mirkwood Wood-elves.) Thranduil was a Sinda whose father, Oropher, was among those of the Teleri Elves who chose not to return to Valinor. Instead, he remained in Middle-earth to serve King Elwe (better known as Thingol, meaning “Greycloak”) in Doriath. (More about him later.) After Thingol’s death, and the Fall of Beleriand, the Sindar Elves migrated into different areas of Middle-earth. Some of the regions they entered were already inhabited by the Silvan Elves, who had not gone to Valinor either. When Oropher crossed the Anduin River into the southern part of the Greenwood, the leaderless Wood-elves, who were already living there, were in such awe of him that they chose him to be their king. At some point after Sauron set up residence in the tower of Dol Guldur, the southern Wood-elves moved into the northeastern e
