Lord of the Drowned Kingdom of Yer-Ks, this king ruled over all the Skrael. Given that the watery kingdom is a kingdom and the Skrael live there, it is only fair to say that they are ruled by a king like the Dwarfs in Myrgard. The Skrael king was never developed into a character by Bungie, but given the content of the world and the powers existing in it--it is fair to assume that such an individual would prove really powerful, a challenge even to the current avatara, (which is probably why the journal entries don't talk about Yer-Ks being invaded by the Dark).
Yer-Ks is home to Sea Elementals, Skrael, Mermaids, Skrael priests, and quite possibly other marine life. The most versatile of the Light forces, the Skrael King commanded the amphibious army with a noble fist. So much so, that he pledged his army to be allies with the light throughout the ages. He is considered to be one of the oldest and wisest of the Light's lords. Having seen the rise and fall of the Cath Bruig Empire and the coming and going of the Leveler many times. King Lir is always a fast friend to be called upon against the Dark.
Out of all the kings, emperors, and avataras--King Lir was closest to Alric and considered him the most just and kind of all the Light's warriors. Though King Lir liked Mazzarin as well, Alric was the only one that did as much for the Skrael as he did his own race--thus King Lir held Alric in high esteem.
In Irish Mythology Lir was considered the God of the Seas.
Skrael King Lir is a very ancient and powerful being. He is able to shoot bolts of energy from his hand (like the stones from Skrael warriors), water attacks (some could put out fires), tornadoes, lightning, teleport, and he can even summon or create sea elementals with his trident. His trident also allowed him to launch a massive tidal wave that blew his opponents apart (much like Mjarin's fire attack in Myth 3).
Lir even had other abilities that were analogous to the sea creatures he commanded--he could shroud his forces from enemy eyes by utilizing magical mist from his body (his army couldn't be seen on the map), regenerate, paralyze victims with black ink, and send out sonic attacks.
Lir's physical prowess was impressive as well. He could move super fast on land or water and was just as versatile in both elements.
Some of his powers were natural, but many powers were granted to him by his magical trident, which he could use for magic or melee. Truly, Alric found him to be the most versatile of his allies with powers and knowledge rivaling his own.