Sky King

The Sky King (天空王, Tenkūō) was a Mysterious Being who ruled the skies and wanted to take Earth for himself.

Appearance
The Sky King was a humanoid bird like being with the appearance of an aging, but very muscular old man. He has long hair, a large nose, wrinkled forehead, sharp teeth and pointed ears. He had two sets of wings on his back as well as talons on his feet and clawed fingers. He also appeared to wear a small crown. His overall appearance is reminiscent to the traditional Japanese Tengu.

Personality
The Sky King appeared to be cruel and rather arrogant, due to his belief that he could destroy the Hero Association with ease, or at least extremely confident in his power and that of his warriors. He coveted to conquer the Earth's surface.

Alien Conquerors Arc
After seeing the Deep Sea King and the Subterranean King perish, he decides he wants to take over the world himself with his four underlings: Hawk, Kite, Eagle, and Falcon. However, all four of them are killed by an unseen enemy. Before he could do anything, he perished at the hands of Melzalgald who treated him like a 'small bug'.

Abilities and Powers
It can be said that he is rather strong considering he was able to seriously jar the Hero Association headquarters. Along with his own powers, he has a group of underlings that obey his every command and all bear the name of birds. Although it's unclear how powerful he is, he is at the very least less powerful than Bang, who was able to withstand one of Melzalgald's hits, while the Sky King was not.

Physical Abilities
Flight: The feathered wings sprouting from his back allowed the Sky King to flight in midair.

Energy Projection: The Sky King has been shown to be able to direct blasts of energy from his mouth.

Trivia

 * The Sky King is the fifth of many "kings" mentioned in the series, the others being the Subterranean King, the Beast King, the Deep Sea King, the Ancient King (anime-only), the Monster King, and the Forest King.