The Guardian of Forever first appeared inStar Trek: The Original Series,and later played a role inStar Trek: Discovery. In 1966, Gene Roddenberry introduced the world to Captain James T. Kirk (William Shatner) and the adventures of the USS Enterprise, beginning what would become one of science fiction’s most beloved franchises. Many of the ideas introduced in the earliest days ofStar Trekremain relevant to the franchise today, and Captain Kirk and his crew remain just as iconic as ever.
In one ofStar Trek: The Original Series’most celebrated episodes, “The City on the Edge of Forever,” Captain Kirk, Spock (Leonard Nimoy), and Dr. Leonard McCoy (DeForest Kelley) travel back in time to 1930s New York City. While there,Kirk meets and falls in love with a soup kitchen operator named Edith Keeler(Joan Collins), who ultimately meets a tragic end that Kirk cannot prevent. With its heartbreaking love story and fascinating time travel premise, “The City on the Edge of Forever” will always be one ofStar Trek’sfinest hours.

The Guardian Of Forever Debuted In Star Trek: The Original Series
The Guardian Of Forever First Appeared In Star Trek: The Original Series Season 1, Episode 28, “The City On The Edge Of Forever”
InStar Trek’s “The City on the Edge of Forever,” a sentient portal known asthe Guardian of Forever sent Kirk, Spock, and McCoy back in time to the 20th century.Located on an ancient planet where timelines converged, the Guardian of Forever created ripples that the Enterprise detected as time distortions. This led them to investigate the planet, where they found the initially inert time portal. As Kirk and Spock speculated about the Guardian of Forever, the portal began speaking to them, explaining that it was ancient and beyond their"primitive"understanding.
Why Star Trek’s “City On The Edge Of Forever” Is So Important
What makes “The City on the Edge of Forever” such an important episode of Star Trek: The Original Series?
After Dr. McCoy inadvertently injected himself with a powerful drug, he dove through the portal in his confused and frenzied state. The Guardian of Forever then revealed that McCoy had significantly altered the timeline, andthe portal sent Kirk and Spock back in time to repair the damage.Kirk and Spock emerged in 1930s New York and began working to find Dr. McCoy. Spock eventually determined that Edith Keeler had to die in order to restore the proper timeline, leading to the tragic end of one ofKirk’s greatest love stories.

The Guardian Of Forever Made A Surprise Return In Star Trek: Discovery
The Guardian Of Forever Returned In Star Trek: Discovery Season 3, Episodes 9 & 10, “Terra Firma”
Star Trek: Discoverybrought back the Guardian of Forever, altering its history a bit in the process. At some point, the Guardian went into hiding due to the Temporal Wars and ended up on the planet Dannus V by the 32nd century. At this point,the Guardian took on the appearance of a man named Carl (Paul Guilfoyle),who tested those who wished to use the portal.
Emperor Georgiou’s Star Trek Timeline Explained (In Chronological Order)
Michelle Yeoh’s Emperor Philippa Georgiou had quite the journey on Star Trek: Discovery, and her story continues in Star Trek: Section 31.
Emperor Philippa Georgiou (Michelle Yeoh) began experiencing debilitating hallucinations inStar Trek: Discoveryseason 3 as a result of traveling from the23rd-century Mirror Universeto the 32nd-century Prime Universe. After learning of a potential cure on Dannus V, Commander Michael Burnham (Sonequa Martin-Green) and Georgiou traveled there, where they found the Guardian of Forever. In the guise of Carl,the Guardian sent Georgiou back to the Mirror Universe as a testto see how much she had changed.

Star Trek: Section 31revealed the origin of how Philippa Georgiou became Emperor of the Mirror Universe’s Terran Empire.
From her perspective, Emperor Georgiou spent three months in the Mirror Universe, although only a few minutes passed for Burnham on Dannus V. As Georgiou had tried to find peaceful solutions while in the Mirror Universe,Carl determined that she had passed his test.He then sent the former Emperor to"a time when the mirror universe and the prime universe were still aligned,“which turned out to be the early 24th century, as seen inStar Trek: Section 31.

Star Trek Tried To Bring Back The Guardian Of Forever Before Discovery
Star Trek: The Next Generation & Star Trek: Deep Space Nine Almost Featured The Guardian Of Forever
In “The City on the Edge of Forever,” the Guardian’s last words to Kirk and his crew (“Many such journeys are possible. Let me be your gateway.")left the door open for the Guardian of Forever to appear in futureStar Trekstories.Although the Guardian of Forever appeared in one episode ofStar Trek: The Animated Seriesand returned inStar Trek: Discovery,otherStar Trekprojects almost featured the sentient portal.
InStar Trek: The Animated Seriesseason 1, episode 2, “Yesteryear,” Spock uses the Guardian of Forever to travel back in time and prevent his own death.

In the original draft for the story that would becomeStar Trek: The Next Generationseason 3, episode 15, “Yesterday’s Enterprise,“a team of Vulcan scientists were studying history through the Guardian of Forever.They inadvertently caused the death of Vulcan philosopher Surak, which drastically altered Vulcan history. The writers behindStar Trek: Deep Space Ninealso considered using the Guardian at one point, but decided against it. There were also rumors that the Guardian would be incorporated into J.J. Abrams’Star Trek(2009) as a way for the Romulans to travel back in time.
The Guardian of Forever remains a memorable part of theStar Trekfranchise.
Star Trek: The Next Generation,Star Trek: Deep Space Nine, andStar Trek(2009) found other ways to incorporate time travel, ultimately deciding to forge their own paths rather than reuse elements fromStar Trek: The Original Series. Still, the Guardian of Forever remains a memorable part of theStar Trekfranchise that could continue to pop up in future projects.