Essjee 78 was an android security guard, working for Safensound, in the spaceport on the planet Epajaenda.
Ace chatted him up for a bit, admiring his green eyes. She realised later that he was an android and was identical to the other android guards.
Essjee 78 and his fellow guards tried to force Ace and the Seventh Doctor to leave the planet, but forgot about them when the Rat King appeared in the spaceport. (PROSE: Last Rites)