Professor Zaroff was a mad scientist who planned to destroy the world in the 1967 Second Doctor story "The Underwater Menace". Some of his scientific inventions included food made from plankton, and the ability to graft gills to humans to enable them to breathe underwater. As part of his diabolical plans, he allied himself with the leaders of Atlantis telling them he would raise their city back to the surface or lower the ocean level by draining the water through a fissure in the Earth's crust.