Svogthir

Svogthir, called the "god-zombie," was the parun of the Golgari Swarm on the plane of Ravnica.

Rise and fall
The guild started as an army of elves and outcasts that Svogthir had united, but most importantly were the undead legions Svogthir himself had raised. Svogthir fought in the name of chaos, but when the war came to a stand still, the paruns of the guilds came together. Szadek proposed the Guildpact and Svogthir was instrumental in convincing the forces of chaos in becoming signatories of the pact. He remained in charge of the Golgari for thousands of years, surviving through his mastery of necromancy, which he used to become a lich. Over time, he improved his physical form and his body was comprised of the remains of various powerful individuals, including the torso of Cisarzim, the Gruul parun. The only original part of his body was his head, which became indestructible thanks to his magics. Eventually, Svogthir was overthrown by five gorgons, the Sisters of Stone Death. Although he managed to kill two of them, the other three were able to rot away his body and then sealed him inside an ancient tomb that came to be known as Svogthos. There Svogthir remained for over a century.

Reappearance
However, the parun reappeared at the time of the Decamillennial anniversary of the Guildpact's signing due to the conniving of Savra, who wanted to use him to overthrow the Sisters of Stone Death. She freed Svogthir from his tomb and constructed a new body for him, which he used to defeat the Sisters, killing another two of them in the process. However, Savra betrayed him, taking over the leadership of the guild herself by taking control of his replacement body, smashing his head and consuming his essence to empower herself.

Last sighting
But Svogthir survived still. When Szadek betrayed and murdered Savra, Svogthir's spirit took over the treacherous elf's corpse. He made an alliance with the Simic guildmaster Momir Vig and the two planned to wipe Ravnica clean using Project Kraj. However, Svogthir's mind was overpowered by that of Agrus Kos, who possessed Savra's body and used it to kill Vig. After that Kraj destroyed Vig's lab where Svogthir was. His fate after this is unknown, but given the tenacity the necromancer had, he likely still exists.