The Thane was a Thane-class replicant, and the product of Cyrene genetic technology.
He, along with his friend Viktor, watched over the mind-wiped Khamirae on a backwater planet after the war the Khamirae were manufactured for ceased to exist. He kept the neuropathic generator in his keep running to pacify the Khamirae's conditioning that transformed them into beasts. When the Khamirae unexpectedly had children, the Thane was able to renew himself by cloning replacements for fifty generations to continue watching over them, while Viktor's systems slowly started to fail. With Viktor's help, the Thane started to collect DNA samples to bolster his own DNA, but his dirty biopsy device caused the villagers to contract septicemia and die.
When the Tenth Doctor and Martha Jones arrived, the Thane had Viktor bring them to the keep. Gideon was able to release the Doctor before Viktor could do this, and the Doctor and Gideon stormed the keep to save Martha. While at the keep, Martha explained to the Thane about what his dirty medical instruments had done to the Khamirae villagers. Martha tried to warn the Doctor not to destroy the Thane's generator, but failed. The generator's destruction caused the villagers to transform into bestial form. The Doctor fixed the generator, but Viktor died protecting him. The Doctor suggested to the Thane to lower the generator's output periodically so the villagers could control their transformations. The Thane decided to help the villagers come to terms with who they were, and refused to clone himself any further. (COMIC: Universal Monsters)