Scaroth was the last of the Jagaroth, a vicious and callous warlike race, appearing in the serial City of Death. The last Jagaroth spacecraft exploded upon takeoff on prehistoric Earth. The energy from that explosion ignited the primordial soup that led to life developing on Earth and also fractured Scaroth into 12 aspects, scattered throughout Earth's history. Each splinter had the ability to communicate with the others, and disguising themselves as human, together they influenced Earth's technological development to the point where the last Scaroth (who had taken the alias of Count Scarlioni) could construct a time machine, travelling into the past to prevent his ship from taking off and thus saving his species and himself.
The scheme was financed by his earlier selves arranging for priceless art treasures to be passed down to Scarlioni. One such scheme involved his 1505 persona, Captain Tancredi, persuading Leonardo da Vinci to paint six copies of the Mona Lisa, so that in 1979 Scarlioni could steal the original from the Louvre and sell all seven copies on the black market.
Sensing the fractures used by the time travel experiments, the Fourth Doctor and Romana stumbled upon Scaroth's plans for the painting and foiled them. Scaroth used the prototype time bubble to travel back into the past anyway to stop his ship from taking off. However, Duggan, a private investigator who was aiding the two Time Lords, punched out Scaroth at the crucial moment. Scaroth was then sent back to 1979 where the time machine exploded, killing him.