Hastur

Hastur is a Great Old One and one of Nyarlathotep's commanders.

He is a major antagonist of Seeds of Evil.

Physical Appearance
As the nickname The King in Yellow implies, Hastur is a golden yellow alien with a rather grotesque appearance, having tentacles to walk instead of legs and a head shape vaguely similar to a triceratops.

Personality
Hastur is a calm and collected individual with a sense of supremacy over the inferior species. He is rather touchy about his shadow, and will attack anybody, enemies and allies alike, who are foolish enough to step in it. However, he is not without a sense of honor, as he will accept a savage beatdown if he grew careless in battle.

Cosmic Lightning Control
Hastur is able to control cosmic electrical energy, especially sprites and blue jets. He can shock enemies that would normally be immune to the element, such as Elefish or Endotopians.

Electrical Aura
Hastur can increase his toughness and stamina by surrounding himself in a bursting aura of electricity. However, this ability can be bypassed by various means.

Gravity Breath
Hastur can gather graviton energy and release it from his mouth, whether the shape was a stream, burst, sphere, ot even a mist. This attack has more than enough power to obliterate entire continents.

Superhuman Strength
Hastur has enough strength to lift objects with seemingly infinite mass and weight, and is able to fight off other beings with high power.

Superhuman Durability
Hastur is tough enough to survive the crushing gravity of neutron stars, so not much is able to kill him.

Immortality
Hastur is immortal and cannot die of natural causes. However, he can be killed by extraordinarily powerful beings, such as Outer Gods and Arkeans.

Giant Form
Hastur can transform into a titanic abomination, which is said to be his true form. In this form, he stands at 433 feet tall. His weight is unknown due to the fact that he floats in his giant form.

Trivia

 * Hastur is loosely based on a Lovecraftian cosmic entity of the same name.