According to the Book of Gib, Tagartis is the chief deity of the Gibcraftian Pantheon. The form of Tagartis is that of a massive, gelatinous blob with a texture like lard. It is said that a part of Tagartis is seen in oil, honey, or any other viscous substance in the world.

On the first day, he created the first world of Gib and set it in motion. It was dark, so he created the sun, and slung the world around it which began the Great Spiral. The second day he placed the moon and millions of stars because the night sky was pitch black. He marvelled at his creation, but he felt something was wrong. He was alone in his existence, so he created a companion.

During the third day, Tagartis secreted out of his body a primordial slime. On the fourth day, the slime congealed into the body of Immaridel who was in the form of a giant, naked man. Immaridel learned to walk and eat on the fifth day, and on the sixth day, Tagartis taught Immaridel about the universe. Until he could fend for himself, Immaridel ate from the body of Tagartis. The pair made big plans together for Gib.

Immaridel eventually became too clingy, so Tagartis helped him create a race of men and demigods. From this point, Immaridel created additional worlds without assistance. Tagartis is hardly seen anymore except when Immaridel is bullied or molested.

Apocryphal accounts state that when the Great Spiral grows cold Tagartis will absorb it into his body, and all of creation will be destroyed.