The original “Star Trek” series may not have lived long, but it prospered.

The TV show ran for three, low-rated seasons on NBC in the late 1960s, but later found a large, devoted following in reruns. The sci-fi series prided itself on its portrayal of an interracial, international cast of characters careening heroically across the galaxy in the starship “Enterprise.”

George Takei, who played Lieutenant Hikaru Sulu on the original series, credits the show’s creator, the late Gene Roddenberry, for this vision. “He said the starship Enterprise is a metaphor for starship Earth,” Takei told the PBS NewsHour in a recent interview. “And the strength of this starship is in its diversity, coming together and working in concert as a team. And he cast accordingly.”

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The Enterprise’s crew, led by Captain James T. Kirk (played by William Shatner), also included crewmembers from Asia, Africa, Europe, as well as one alien named Spock (played by the late Leonard Nimoy). The crew’s overarching mission, as Kirk declared in the show’s opening credits, was “… to seek out new life forms and new civilizations. To boldly go where no man has gone before.”

While the crew of the Enterprise dealt with alien races both friendly and hostile, “Star Trek” also pushed some taboo social boundaries. The 1968 episode “Plato’s Stepchildren” showed one of the most prominent interacial kisses ever seen at the time on American TV, when Captain Kirk kissed Lieutenant Nyota Uhura (played by Nichelle Nichols). That kiss caused several TV stations in the South to black out the episode in protest.

Roddenberry hoped the Enterprise crew would give American viewers a broader view of humanity, and so many have wondered why he never included any LGBTQ characters on his show. (For context, the debut of openly gay characters on primetime TV came a few years after the end of the original “Star Trek.”)

Takei is gay, and since his time on “Star Trek,” has become an enormously popular LGBTQ rights activist. I asked Takei if he ever talked with Roddenberry about that omission on the show.

Takei said Roddenberry wanted to have a gay character but said he feared network executives would balk and might cancel the show. Takei described Roddenberry telling him, “I’d like to do that, but he said ‘I’m walking a tightrope.’ The interracial kiss was very controversial.”

For “Star Trek,” a pioneer in so many ways, it took 51 years for the franchise to finally feature an openly gay character.