Star Trek: Five people you should know
If you only learn about five people from the original Star Trek series (an arbitrary number, I know), here are my picks:
James T. Kirk is the charismatic captain of the USS Enterprise. He's always first to go down and explore a new planet (and the first to fall in love with any beautiful alien women on its surface). Kirk is impulsive, romantic, hot-headed and resolutely human.
Mr. Spcok is the half-human, half-Vulcan chief science officer of the Enterprise. Vulcans are an alien race whose culture is based on valuing logic above all else. As such, Mr. Spock provides a cool-headed, rational foil to Captain Kirk's impulsiveness.
Dr. Leonard "Bones" McCoy is the ship's doctor. He, Kirk, and Spock form the core group that usually goes down to explore the surface of a new planet and deal with any inhabitants. If Kirk is an idealist, Bones is gruff and more grounded in matter-of-fact reality.
Montgomery "Scotty" Scot is the ship's chief engineer. He also runs the transporters and has a reputation as a "miracle worker" who can fix the unfixable and generally use technology to save the day.
I wouldn't say that Uhura's job as communications officer is particularly more important than Sulu or Chekhov, but her role as a black woman who was a respected professional was a Big Deal in the 1960s.
One anecdote which illustrates her impact is the story of Caryn Johnson, who first saw Star Trek when she was nine years old and ran through the house calling "Momma! There's a black lady on TV and she ain't no maid!" (Young Caryn Johnson later grew up to become an award-winning actress who frequently guest starred on Star Trek: The Next Generation. She is better known by her stage name: Whoopi Goldberg.)
Bonus: Nurse Chapel
The role of Nurse Christine Chapel on Star Trek isn't particularly notable, but the actress who played her, Majel Barrett, was one of only two actors to appear in both the failed first pilot and in the successful second pilot. (In fact, she was originally cast as the first officer of the Enterprise. The other actor to appear in both pilots was Leonard Nimoy.) She later married Gene Roddenberry and had guest roles or did voiceover work in every television series in the franchise, so I figured I'd introduce her here.