King of the Wood ~ Thranduil the Great

Thranduil has taken quite a beating in this regard, mostly at the hands of those who will not acknowledge his side of the controversy within the scope of The Hobbit. However, as King he acted well within his rights, for as Maedhros astutely observed, "A king is he that can hold his own, or else his title is vain." (Of the Return of the Noldor, The Silmarillion)

Thranduil was plainly and readily named by the silvan elves as "their greatest king." In this they set him above even his father Oropher who had founded their realm, a remarkable fact considering that it was during Thranduil’s reign that Greenwood was darkened, perpetual war brought to their borders, and they themselves driven underground in the far eastern corner of a sadly diminished domain. Obviously, Thranduil’s claim to greatness rested upon something other than overall national prosperity. Otherwise he would have to be the worst of the lot.

He seems to have even eclipsed Oropher’s memory in the histories, whether it be an editing glitch or whatever: "Most of [the High Elves] dwelt in Lindon west of the Ered Luin; but before the building of Barad-dur many of the Sindar passed eastward, and some established realms in the forests far away, where their people were mostly Silvan Elves. Thranduil, king in the north of Greenwood the Great, was one of these." (Appendix B, LotR, RotK)

His people loved him, as can be subtly observed throughout, but explicitly at the Battle of Five Armies, when "the elf-lords were at bay about their king," defending him with their lives. Even Bilbo then "preferred on the whole to defend the Elvenking," for by that time the hobbit knew him reasonably well, having haunted his halls unseen for some weeks before.

It should be remembered that Thranduil alone survived into the Third Age with never a Ring of Power. While Lindon, Rivendell, and Lothlórien were at least at one time maintained by a ring and its bearer, Thranduil maintained his foothold in the north by the seat of his pants, and likely a good bit of blood, sweat, and tears. It takes an uncommon king to hold his own together throughout centuries of siege and sacrifice, while at the same time maintaining them as "a merry folk," and only that stripe of indomitable charisma can truly be called great.