‘Star Trek’ 101: 22 Must-See Episodes to Mark the 50th Anniversary (Videos)

“Where No Man Has Gone Before” (Star Trek)

Anyone looking to get into “Trek” should start with the original series’ second pilot, which NBC picked up after Lucille Ball urged the network to give the show another chance. In it, Kirk is forced to decide between killing a power-corrupted Enterprise crew member or putting the ship at risk. It’s an early example of the ethical dilemmas that would become part of the series’ core.

“Balance of Terror” (Star Trek)

This episode from the very first season of the series introduces the Romulans, a war-like race that frequently locks horns with the Federation throughout the series. Spock leads the Enterprise into a battle against a brilliant Romulan commander in an episode that examines the nature of war and how people who find themselves enemies to each other can have more in common than it may first seem.

“The City On The Edge Of Forever” (Star Trek)

One of the most heartbreaking episodes of the original series. A disruption in the time-space continuum requires Kirk, Spock, and McCoy to travel to 1930s New York to stop the Federation from being erased from existence. The price Kirk must pay to save the future will haunt him forever.

“Devil In The Dark” (Star Trek)

Named by William Shatner as his favorite episode, this story shows the crew trying to fight a subterranean creature killing members of a mining colony. Their plans get turned upside down when they realize the true motives behind the creature’s actions.

“Measure of a Man” (Star Trek: TNG)

“Star Trek: The Next Generation” took a while to get out of the shadow of its predecessor, but when it did, it produced some TV classics. Here, Captain Picard is challenged to prove that his android lieutenant Data is a sentient being deserving of human rights, leading to one of Patrick Stewart‘s finest speeches in his acting career.