The Doctor, an Emergency Medical Hologram (EMH), is a fictional character portrayed by actor Robert Picardo in the television series Star Trek: Voyager, Star Trek: Prodigy, and Star Trek: Starfleet Academy. He is an artificial intelligence manifesting as a holographic projection, and designed to be a short-term adjunct to medical staff in emergency situations. However, when the USS Voyager is stranded on the far side of the Milky Way galaxy without medical personnel, he is forced to act as the starship's permanent chief medical officer. In an example of the Star Trek franchise's exploration of artificial intelligence, a rudimentary algorithm becomes a major character in the show.
Casting
In a 2020 interview, Picardo said his agent told him that he was selected from 900 actors who auditioned for the role.
He added that he first learned what a hologram was from being selected for the role. "I was confused, I didn't know what it meant for him to be a hologram or a computer program. I didn't understand enough about Star Trek 'science,' which is based on real science, although we still don't know how to make a hologram with density. So I got the part without knowing at all what I was in for." During his audition for the role of The Doctor, Picardo was asked only to say, "Somebody forgot to terminate my program." However, he then ad libbed, "I'm a doctor, not a nightlight!" (Picardo was initially afraid that he might have ruined his chances—ad libbing, he explained, was something that one just "did not do" in an audition.)
Depiction
The Doctor begins his service on the USS Voyager as the standard Emergency Medical Hologram (EMH) built into almost every newer Starfleet ship's sickbay. The EMH is to be used should the ship's doctor be incapacitated or require emergency assistance. In the series' first episode, Voyagers chief medical officer, along with his nurse, are killed, necessitating extended use of the EMH. The EMH eventually develops his own personality, although he generally maintains his acerbic wit and irritating "version one" bedside manner. As he was originally intended as a temporary medical backup system, not as a digital life form, Voyagers journey strains his programming to some limits. He gives himself a name during episode S1E12 Heroes and Demons, "Schweitzer". (This name did not carry throughout the entire series.) The Doctor becomes the chief medical officer, with Kes and Tom Paris at various times acting as nurses.
Attempting to develop a realistic personality, the Doctor not only manufactures a holographic family ("Real Life"), he also has an increasing number of other "human" experiences. This results in the Doctor's program evolving to become more lifelike, with emotions and ambitions. He develops meaningful and complex relationships with many members of the ship's crew. The Doctor also develops talents as a playwright, artist, and photographer, and even becomes a connoisseur of opera. He has multiple other experiences with "family", including having a son with a "roommate" while trapped on a planet for three years. During the episode "Blink of an Eye", he asks an associate to inquire further about his progeny.
A recurring theme are the ethical aspects of an artificial, yet apparently sentient, being. In the episode "Latent Image", treating two patients with an equal chance of survival, with only enough time to treat one, The Doctor chooses Harry Kim, a friend. The other patient, Ensign Jetal, dies. The Doctor is overwhelmed with guilt, believing that his friendship influenced his choice. When the stress nearly leads to his program breaking down, Captain Janeway has his memories of these events deleted. When The Doctor later discovers clues as to what had happened, Captain Janeway is convinced by him and others that he has a right to learn to come to grips with the guilt in the manner of any other sentient being rather than be treated merely as a defective piece of equipment.
The Doctor submits a holonovel titled Photons Be Free to a publisher on Earth, detailing the manner in which holograms are sometimes treated by Starfleet. His characters are closely based on Voyagers crew, but exaggerated to appear more intense and vicious, creating fears among the crew their reputations would be ruined. Tom Paris convinces The Doctor to make adjustments without sacrificing his theme. The Doctor lacks legal rights as Federation law does not classify him as a "sentient being". Thus he is forbidden to make any subsequent changes to the holonovel. Captain Janeway's efforts result in The Doctor being accorded the status of "artist", although not a "person". This permits him to rewrite the novel. Four months later, it is known throughout the Alpha Quadrant as a very thought-provoking piece of work. Several other EMHs, now relegated to mining duty, experience the novel.
The Doctor's standard greeting is "Please state the nature of the medical emergency" when activated, though later modified to say whatever he chooses. In "Jetrel", it is revealed that he was given the ability to activate and deactivate himself.
The Doctor later acquires a mobile holographic emitter from the 29th century ("Future's End"). Although he has previously been confined to Sickbay or the Holodeck, the mobile emitter allows The Doctor to move about freely, making him ideal for missions where the environment would be harmful or otherwise fatal to the crew. In one notable incident, when an away team is trapped on a radioactive planet, The Doctor is able to infiltrate the people and almost single-handedly rescue the team because, as he points out, being a hologram renders him immune to the radiation, stating that "being a hologram does have its advantages." The Doctor continues his use of the emitter in Star Trek: Prodigy and Starfleet Academy.
In a 2020 interview, Picardo recalled his initial reticence to the concept of a mobile emitter: