The Doctor, an Emergency Medical Hologram (or EMH for short), is a fictional character portrayed by actor Robert Picardo on the television series Star Trek: Voyager, which aired on UPN between 1995 and 2001. He is an artificial intelligence manifesting as a holographic projection, designed to act as a short-term supplement to the medical staff of a starship during emergency situations. However, when the starship Voyager is stranded on the far side of the galaxy with no surviving medical personnel, he is forced to act as the ship's chief medical officer for several years. In an example of the Star Trek franchise's exploration of artificial intelligence, a simple software program becomes a major character in the show. Source: Wikipedia (en)