Dr. Abraham Van Helsing from Dracula: The world's pre-eminent vampire expert and monster hunter got his start as a humble medical student. He still loves his medical training, but he wanted a little more fun out of life.
The Doctor from Star Trek: Voyager: He may just be a hologram, but the crew of the Voyager couldn't get by without The Doctor. By the end of the series, it's probably safe to say he couldn't get by without them, either.
Dr. Zira from Planet of the Apes: As a "veterinarian" among the Apes, Zira's responsible for caring for and learning about humans, but her true compassion for them is what made her one of the franchise's most endearing characters.
Dr. Leonard "Bones" McCoy from Star Trek: Others may have come before him, but when you put the words "science fiction" and "doctor" together in your head, Bones is likely still the first name that comes to mind. Maybe it's because of his unshakeable determination in the face of danger, but we're guessing the catch phrase has a lot to do with it too.
Dr. Helena Russell from Space: 1999: She signed up for a mission to the Moon and ended up riding the Moon out into the far reaches of space. It was an adventure she never expected, but we love the way she handled it.
Special Agent Dr. Dana Scully from The X-Files: In addition to her highly scientific mind and full FBI training, Scully also brings a medical degree to the X-Files party. Which is good, because her partner was almost dying all the time.
Dr. Beverly Crusher from Star Trek: The Next Generation: She's a nearly unflappable medical mind, a single mother and a well-respected member of the Enterprise crew, and she's still got time to nurture some sexual tension with the Captain.