The Dark One, also known as the Desert Muck Leech, is a creature that lived on Mars, also serves as the main antagonist of the fourth and final Futurama film Into the Wild Green Yonder. He was almost killed by Leo Wong, but Leela saved him from poisonous cement that had killed the rest of his species. He again escaped death when Zoidberg almost ate him. Again, Leela saved him and he became the Eco-Feminist mascot. He was later zapped by the Last Encyclopod and killed: Zoidberg ate the remains.
Primordial EraThe Dark Ones were a great race of evil beings. They evolved from a species of either snakes or frogs who had roamed the universe with the mission to destroy all other lifeforms.
Over time, they had evolved into the Desert Muck Leech, which dwelt on Mars in a small puddle. They also evolved to have the power of Telepathy, and Psychokinesis (Telekinesis). Additionally, they are immune to mind reading (possibly due to a lack of the Delta Brainwave like Fry).
One notable Dark One was a Desert Muck Leech, but in their evolution, they could have been genetically divided into different species. However, it is possible that the "Legion of Mad Fellows" could be searching for them to "revive" the fallen Dark Ones, for behind their misdeeds, they do not deserve to be torn from existence.
The Dark Ones nearly became extinct when Leo Wong built a parking lot over their living quarters on Mars for the new Mars Vegas, but Turanga Leela saved one of them. Before meeting its end, it managed to kill Frida Waterfall and her brother, Hutch Waterfall.
In their competition are the Encyclopods, whom tried to save all the endangered species that the Dark Ones threaten by storing their DNA. For a long time, the Encyclopods had been extinct, and the Dark Ones were thought to have won. However when the Chi redeveloped and spawned new life in the Violet Dwarf System, the Dark Ones met their end when they destroyed by the new Encyclopod.
The new Encyclopod would have saved the DNA of the Dark Ones, but Zoidberg ate its remains before its DNA could be extracted.