Star Trek: The Next Generation is one of the most popular and well-loved TV shows in history for a variety of reasons, but the cast of compelling and unique characters could be one of the deciding factors. Few other shows in the Star Trek universe have the same dedicated following or the level of success when it comes to recruiting new fans.

RELATED: Star Trek Fan Theories That Turned Out To Be True

Every television show has a main cast, a supporting cast, extras, and "one-off" characters. These are the memorable figures that carry the story and act as the emotional center for the plot for a single episode, and despite how interesting they are, we only saw them on TNG once.

7 Stephen Hawking, "Descent."

stephen-hawking-star-trek TNG-cameo descent

Many of the characters that only appear once in Star Trek: TNG are celebrity cameos, and this is a unique instance in which the actor plays himself. Considering the nature of Star Trek and its groundbreaking science fiction pedigree, it would have been nice to see him more often.

Hawking appears in a holodeck poker game that also includes Isaac Newton and Albert Einstein. Data has created the game as an experiment of sorts to see how three of history's greatest scientific minds would react under certain circumstances.

6 Ensign Robin Lefler, "The Game" and "Darmok."

Wesley Crusher and Ensign Robin Lefler, The Game

Okay, this is two episodes and maybe it's cheating right at the start, but this character barely got to do anything in "Darmok" which was focused on Picard's talents as a diplomat. She's an important character in "The Game," however, and since both of these roles were the first time Ashley Judd appeared on TV we thought it was worth a mention.

RELATED: Star Trek: A List Of All The Movies And Shows On Paramount+

The Game is a typical 1990s anti-drug message that's very much a product of its time, but it's not as authoritative or oblivious as the kind of thing that kids were taught in schools about addiction being some kind of moral failing. Ensign Lefler is just as smart and capable as Wesley Crusher, and she does have a larger role in the lore but never appeared on the show again.

5 Benjamin Maxwell, "The Wounded."

benjamen maxwell the wounded star trek tng

A historic episode that gave the fans some TNG and Deep Space 9 crossover, this was one of the first episodes to feature the character of Miles O'Brien in the main role. It also focused on a famous Starfleet captain called Benjamin Maxwell, who has a lot of backstory and lore to back him up but only appears in one TNG episode.

Bob Gunton plays the role of Maxwell, who has a penchant for authoritarian roles, and here he plays an antagonist but a sympathetic one. In the end, it's O'Brien, his former crewmate, who talks him down from attacking the Cardassians and destroying a fragile peace. He's under arrest by the end of the episode but that's the last the viewer hears of him.

4 Kamala, "The Perfect Mate."

Kamala-The-Perfect-Mate-1

Most people think of Famke Janssen as Jane Grey of X-Men fame or the Russian femme fatale Xenia Onatopp from Goldeneye. This time she takes on the role of a powerful empath, Kamala. She falls hard for Captain Picard, the first person she ever met who loves her for who she is.

RELATED: Star Trek: Picard's Biggest Mistakes & Failures

Fans of The Original Series will be reminded of "Elan of Troylius" but with a modern veneer. The plot is essentially the same: the Captain falls for a woman he's escorting to a wedding that's already been arranged to end an ongoing war, but this is better written and better acted than the vintage one.

3 Lanel, "First Contact."

TNG30-First-Contact Lanel and Riker

If Candid Camera existed in the 25th century, Riker might have thought he was the show's new star when Lanel offered him an interesting deal. Help him escape and satisfy her alien-sex fantasy. The episode was a joke on the oversexed alien trope, and Lanel is played to perfection by Bebe Neuwirth. Viewers might remember her as the cool yet smoldering Lilith from Cheers.

The story begins with Riker disguised as a local to investigate whether a certain civilization is ready to enter the Federation or not. It's an interesting premise that gives the fans more insight into how Starfleet admits planets or civilizations with a comedic twist.

2 John Doe, "Transfigurations."

OBrien_and_John_Doe Transfigurations

This is one of those episodes where science fiction takes on a spiritual theme and it's well done. The crew rescues a lone survivor from a damaged escape pod, and even though Dr. Crusher is sure he will survive thanks to some mysterious cell mutations he has no recollection of how he ended up in the escape pod.

RELATED: Great Sci-Fi Shows That Start Off Slow

The crew calls the character John Doe, the traditional name for an unidentified person, and soon it's revealed that he seems to have miraculous healing powers. It turns out that his race is on the verge of evolving into a species of higher beings that consist only of energy, and those that fear the change are telling the population that the mutations are a deadly sickness. Eventually, John fully evolves and escapes, and although he doesn't appear again, it's suggested that he returned to his home world.

1 Soren, "The Outcast."

soren star trek tng the outcast

It was a daring LGTBQ allegory in a time when gay marriage was still illegal and shows like Queer As Folk was a few years away. This episode has a strong fanbase, is still relevant today, and is cited as one of the earliest and best illustrations of the rights of non-binary people.

Soren was a character from a species without gender and started a relationship with Riker during their tenure on the Enterprise. Despite her cultural background, however, Soren identified as female, and the judges of her society called this "sick" and she was sent back to their home planet for "re-education." We never saw Soren again, but she made an impression.

MORE: The Best Star Trek Movies, Ranked