The Doctor (Star Trek)

The Doctor is a character in Star Trek: Voyager. He is an Emergency Medical Hologram based on the appearance and personality of his creator, the engineer Doctor Lewis Zimmerman. He was created to be an emergency supplement, but when Voyager became stranded in the Delta Quadrant (70,000 light-years from Earth) with their chief medical officer dead, he was activated to fill the role. His character developed throughout the series as he made friends, expanded his programming, and gained a mobile emitter that allowed him access to the entire ship (previously, he had been confined to sickbay).

It is worth noting that The Doctor had several hundred 'cousins' - other EMHs who were decomissioned and set to work as labourers.

Doctor Fitzgerald of the Medical Department looks suspiciously like him. As much of Medical's technology is similar to or the same as that of the Trekverse, it is not far-fetched to speculate that Doc Fitz is an EMH.