Carlo (The Vampires of Venice)

Carlo was the Human steward of the Saturnynians.

Biography
Carlo was often seen at his masters' side, at one point even reading out the death sentence for Isabella.

Despite having taken part in his masters' machinations and rituals, Carlo did not seem to have known their true nature. He seemed bewildered by Rosanna's appearance when her perception filter began to fail. As her plans for Venice became clear and a storm appeared over the city, he escaped the manor with some valuables. His ultimate fate following Francesco and Rosanna's deaths remains unknown. (DW: The Vampires of Venice)

Due to the Cracks in time being negated, it is most likely that Saturnyne was never lost and the Saturnynians never came to Earth, therefore Carlo never worked for the Saturnynians.

Behind the scenes

 * Despite being referred to by name in the episode's dialogue, Carlo is only listed as 'The Steward' in The Vampire of Venice's credits.