Origin

Sethe is an omnipresent force of death and pestilence that has caused all the major plagues that have ravished human kind from the beginning of time. Sethe, along with his armies of the dead, have fought against the green since the moment life and death became real, with each side using animals and creatures from the current time period (ex. zombie dinosaurs and plant based mammals and reptiles.)

Creation

Sethe was created by Swamp Thing writer Scott Snyder. 

Major Story Arcs

Swamp Thing

Shortly after Alec Holland's return to the world of the living, a great threat emerges in the desert, in the form of Sethe. Holland, who is trying to escape his past, is eventually contacted by a Swamp Thing from the Parliament of Trees to inform him of the threat of Sethe, who the Swamp Thing describes as the ultimate enemy to the Green and life itself. Swamp Thing tells Holland that he is the chosen champion of the Green, and it is up to him to stop Sethe before the being destroys all life.