The character was more introspective than Howard's subsequent creation, Conan the Barbarian, whose first appearance was in a re-write of a rejected Kull story.

Kull was born in pre-cataclysmic Atlantis c. 100,000 BC, depicted as inhabited at the time by barbarian tribes.

East of Atlantis lay the ancient continent of Thuria, of which the northwest portion is divided among several civilized kingdoms.

Howard coined the term while tying Kull's world to Conan's in the 1936 essay "The Hyborian Age".

Kull lost his ship and crew in a naval battle off the coast of Valusia, but once again survived.

After proving to be an effective combatant and gaining fame in the arenas of the capital, a number of admirers helped him to regain his freedom.

In "The Curse of the Golden Skull" Kull, approaching his thirties, is recruited by King Borna of Valusia in a mission against the ambitious sorcerer Rotath of Lemuria.

In "The Shadow Kingdom", Kull has spent six months upon the Valusian throne and faces the first conspiracy against him.

The conspiring of his courtiers leaves Kull almost constantly threatened with loss of life and throne.

However, this story was written many years after the death of the original author of Kull and Conan, Robert E. Howard.

First Councillor Tu is a trusted administrator, but also a constant reminder of the tradition bound laws and customs of Valusia.

Ka-Nu (sometimes named Kananu), the Pictish Ambassador to Valusia and wise man, is responsible for the friendship between Kull and Brule despite the ancient enmity between Atlanteans and Picts.

He is seemingly invulnerable, boasting after being trampled by one of Kull's comrades that he feels "only a slight coldness" when being injured and will only "pass to some other sphere when [his] time comes".

While Conan is a notable womanizer, finding a new love interest in nearly each of his stories, Kull is repeatedly mentioned as uninterested in having any such attachment.

While highly chivalrous and on several occasions helping pairs of star-crossed lovers reach a happy consummation, he is never mentioned as having himself any relationship with a woman.

Patrice Louinet writes in "Atlantis Genesis"[5] that Howard may have been influenced by the work of Paul L. Anderson and his novellas published in Argosy in the 1920s.

Louinet notes Howard's stories echo Anderson's subject (how the Cro-Magnons supplanted the Neanderthals).

There is a possibility that Kull's name comes from Old King Cole, who was mentioned in "The Search" by Edgar Lee Masters, published in Cosmopolitan, a poem Howard had "been trying to re-discover".

[10] In 2024, Arrow Comics published an adaptation of "The Shadow Kingdom" written by Randy Zimmerman with art by Russ Leach.

1) #1–9 The 1982 Conan the Barbarian film starring Arnold Schwarzenegger borrowed many elements from Howard's Kull stories.