Absolom Sleed
Absolom Sleed, usually known as just Sleed, was a being who clashed with the "Stratum Seven Agent" twice.
History
Sleed's forces managed to capture the planet Sharabeth using malignant advertising. They warped the planet - making it into a hellscape. This hellscape was explored by the Agent and Kara Delbane after they were sent to the planet, eventually leading to the Agent shooting a body inhabited by Sleed.
However, this didn't kill Sleed - as he was able to possess a being - presumably one of the Oblivion Angels - after tech containing Sleed's mind was liberated by the Oblivion Angels from Sharabeth.
Some years later, Sleed began an elaborate plan to take over the Proximan Chain using the same technique he used on Sharabeth. To distract the Stratum Seven Agent - who lived on the Proximan Chain - Sleed made an elaborate plan that involved killing Kara Delbane and weaving an elaborate web of clues. This, however, didn't stop the Agent from stopped Sleed's plan. (PROSE: Return to the Fractured Planet)