Kroagnon

Kroagnon was the Great Architect of Paradise Towers. He had previously designed Golden Dream Park and the Bridge of Perpetual Motion. When he created his masterpiece, Miracle City, he refused to move out, unwilling to let the residents ruin his work by moving in. He was eventually forced out, but left behind booby traps that killed many of the residents. He fled to Earth and built Paradise Towers, but when he again tried to prevent people from living in his creation, his disembodied mind was exiled to the Towers' basement.

Later, several years after most of the Towers' residents left to fight in a war, Kroagnon began using the robotic Cleaners to kill the ones who stayed behind, but was opposed by the Seventh Doctor. After he took over the Chief Caretaker's body, Pex sacrificed his life to kill Kroagnon. (DW: Paradise Towers)