Lee Jong-hui ( ), also known by the pen-name S.I.U. ( Slave In Utero ) is the creator of Tower of God. Having majored in visual arts education at the university level before being conscripted into the South Korean military, S.I.U. started drawing cartoons at the advice of a senior in the army. During this period, S.I.U. drew ten books' worth of practice cartoons, which formed the backbone of the Tower of God comic he later started to create for the Internet.
“S.I.U.’s fluidly lined art, rendered in a classic manga style, features subdued colors and predominantly black backgrounds, imparting a void-like immensity that complements the setting’s expansive, fantastical inner workings.” —Publishers Weekly