Everyone from Tom Morello to King Abdullah II of Jordan wants to be a part of "Star Trek," though not every guest making a cameo gets a barn burner of a role to show off their acting chops. Fleetwood Mac drummer Mick Fleetwood was so eager to cameo that he agreed to appear as an unrecognizable fish-man — but at least he got to be beamed up!

Other guest stars succeed so well that they become near-permanent fixtures, like Whoopi Goldberg as Guinan, and John de Lancie as Q. Equally poignant, sometimes, are the ones that show up only once and put in an unforgettable performance. Some of them change a story's trajectory or make a lasting effect on a main character's life. Some are terrifying. And some break our hearts. These are 13 of the best one-off guest characters in "Star Trek: The Next Generation." They're not all played by big names. But they made a big impact, and that's what matters most.

Thadiun Okona

Played by Billy Campbell ("The Rocketeer"), Thadiun Okona might not be a full-on space pirate, but he's got the style down pat. He's an unnecessarily sexy smuggler from the Han Solo school of rugged good looks, and in "The Outrageous Okona," he finds himself in the middle of a relationship boondoggle that's almost Shakespearean in its initial complexity.

Okona leans on his flamboyant charm as a tool — along with his healthy libido, as Riker notes. Game recognizes game — much to Picard's annoyance, and that makes it easy to accuse Okona of being a jewel thief and a home wrecker. But as the episode reveals, he's not that bad of a guy. Okona plays by honor, mostly, and he's clearly a sucker for a good love story. He's a sly delight that fans wouldn't have minded seeing more of in canon. Unfortunately, that would take a couple of decades to happen. Okona first returns as a DJ in the "Lower Decks" episode "An Embarrassment of Dooplers," but it's his still-rakish and newfound survival skills — cowardice, really — that made him an equally terrific guest star in two episodes of "Star Trek Prodigy."

It's worth noting that Campbell — who was a finalist for the role of Riker — appeared strictly as a visual joke in "Lower Decks" but voiced Okona for his two "Prodigy" installments.

Dr. Timicin

David Ogden Stiers had a tough task in "Half a Life." As Dr. Timicin, he's the latest lover of the scene-stealing Lwaxana Troi and a scientist from a world with a specific culture built around aging and mortality. Timicin already has a lot on his hands, then, while his real problem is trying to save his people from a dying sun.

It's meant to be a Lwaxana episode, and Majel Barrett-Roddenberry is as vibrant and fun as ever, and delivers dramatically as well. Lwaxana doesn't take Timicin's big reveal well, lending her unexpected depth. Despite his scientific contributions to the current fate of his planet, Timicin is also preparing for his scheduled death at the age of 60. Stiers — the late, great "M*A*S*H" star — plays Timicin as stoic but not unmoved by his plight. Much of the episode fixates on the implications of his decision whether or not to comply with the traditions of his homeworld. He's visibly torn between his duty to his family and his love for Lwaxana. Duty may win out, but his dignity never wavers. It takes a solid force to mesh with Lwaxana Troi and Barrett-Roddenberry, and Stiers succeeds handily. It's the sort of performance that adds a subtle afternote to every appearance of Lwaxana thereafter. Timicin may be gone, but he left a living memory behind.

Gul Madred

You can't go wrong with a David Warner appearance in anything, especially "Star Trek." The genre veteran had already portrayed different, memorable characters in the most recent "Star Trek" films, including Chancellor Gorkon, an influential Klingon diplomat whose death in "The Undiscovered Country" changes the trajectory of history. In 1992's "TNG" two-pater "Chain of Command," Warner rounded out his trio of "Star Trek" appearances with his turn as Gul Madred, the Cardassian torturer who nearly breaks Captain Picard.

It's a tough storyline to watch, but one of the show's finest. Captured after a special ops mission goes awry, Picard's first meetings with Gul Madred are threatening but genteel. Madred quickly establishes power over his prisoner, leaving Picard with few tools to assert himself. The majority of Madred's abuse of Picard happens in "Part II" and is relentlessly paced as we watch the physical and psychological decay of a man who's been nothing but stoically reliable throughout the series. Like his time as a Borg, what Gul Madred does to Picard leaves a lasting mark on his psyche. It's in the final minutes that we discover just how close Madred actually came to breaking Picard. The ugliest part of all is how real it feels, courtesy of Warner's nuanced performance.

Kamala

Famke Janssen plays Kamala, the titular character in "The Perfect Mate." A diplomatic honeypot destined to bridge two worlds and bring peace to both via her marriage, she's a twist on the trope of princesses without any agency of their own. And although she's as alluring as anyone could possibly be, Kamala is bright, educated, and thoughtful. Her accidental fixation on Picard presents us with an interesting question: Would she be as intelligent and incisive if she'd bonded to anyone else?

Janssen's Kamala seems unbothered by the questions of possible sex trafficking going on here, a point Dr. Crusher brings up. Kamala was raised for this outcome, but after her time with Picard, she chooses it of her own free will, and determines to be her own person with her assigned mate. It's subtle but poignant. It would be easy to consider Kamala a chess piece, but Janssen's performance transforms her into something formidable behind all of her elegance. Yes, it was a bit weird to see Janssen and Sir Patrick Stewart together just a few years later in the "X-Men" adventures, but both are such professionals that there's little confusion as to their roles or dynamics in either franchise

Dr. Stephen Hawking

Dr. Stephen Hawking's cameo in "Descent" remains a landmark "Star Trek" moment for one neat reason that was understandably repeated in most of his 2018 obituaries: So far, he remains the only person to have played themselves in the franchise, not counting historical footage of presidents and whatnot. Professor Hawking snagged a great scene, to boot. He plays poker with some of the greatest minds of scientific history — and Lt. Commander Data.

It's observational science at its finest. Data uses the holodeck to summon Hawking, Isaac Newton, and Albert Einstein for a few rounds of cards. The point isn't to talk shop, but to see how the high-stakes game of poker brings out the humanity of these men. Newton isn't impressed with the game, much less hearing Hawking mock his famous apple anecdote, but when Hawking turns out to be quite a card sharp, Newton grows a bit cranky about the way statistical improbability stacks everything in the physicist's favor. Hawking, meanwhile, grins and enjoys it. It's clear the legendary scientist is having a ton of fun. So is the audience.

Captain Morgan Bateson

"Cause & Effect" features another small but cool cameo, but in this case, it also offers a great payoff. With Jonathan Frakes in the director's chair, a complicated story about the Enterprise trapped in a deadly time loop becomes easy to follow. Smartly, it uses fresh footage and new angles, instead of recycling the same shots.

Frakes spins a tight story, utilizing only a few sets, and the crew's success at breaking free from the time loop comes at a price. The loop's been happening since before the episode started, and it's only at the end that we find out why. Two ships were on a collision course inside a temporal glitch and the other Federation ship, the Bozeman, has been missing for over 90 years. Its captain, Bateson, is played by Kelsey Grammer. When the episode aired in 1992, imagine the surprise of fans when, not only did we get to see the Kirk-era movie costumes on the rescued ship's bridge, but Frasier Crane was in charge! Today the impact isn't as wild, but it's still a terrific scene. Bateson, who adapts to the new century just fine, gets a call-back in the "Lower Decks" episode "Grounded," as part of the special operations dream team that exonerates Captain Freeman.

Berlinghoff Rasmussen

What a name! Berlinghoff Rasmussen, played by the ever-eccentric Matt Frewer ("Max Headroom"), is a scam artist with a neat gimmick. Much of "A Matter of Time" taps into our instant suspicion that this time-traveling scientist is up to something scummy. He's way too interested in Data, he's pocketing medical instruments, and Deanna Troi flat-out informs us he's not telling the total truth about his intentions. But he passes the initial sniff test, and, lucky for the audience, he gets to gadfly around the ship for most of the hour.

Frewer is a terrific character actor that knows what he excels at, and he doesn't try to mimic Robin Williams, who'd originally been meant for the Rasmussen role. Rasmussen is charming, eccentric, and can weaponize his annoying curiosity, but he's also not camp. There's an edge to Rasmussen, and his dismay at his failure to scam the Enterprise and return to his real time period — the past, of course, not the future — feels completely honest. It's a bitter irony for Rasmussen that he's about to become what he intended for others: An experimental figure who's out of time.

Captain Edward Jellico

Ronny Cox causes an instant reaction in anyone that loves 1980s action movies. As loathsome white-collar businessman Dick Jones in Paul Verhoeven's "RoboCop" and tyrant CEO Cohaagen in "Total Recall," Cox has played some of the best villains in the business. So, his appearance in the "Chain of Command" two-parter may prompt viewers to reflexively flinch, waiting for Cox's Captain Jellico to be a jerk. And boy, does the guy deliver.

Jellico isn't a true villain, just a too-strict commander in charge of a crew that's already stressed over the missing Captain Picard. He goes head to head with Riker again and again, to the point that Riker gets demoted as first officer in favor of Data. Ultimately, Jellico is revealed as a hard-headed bastard, but he's also got Starfleet's best interests at heart. It's his unflinching steel that gets the Cardassians to give up their valuable prisoner — and, for us Troi fans, it's his by-the-book attitude that finally forces her to wear a normal, comfortable uniform.

The character is a layered-enough dude in his one big appearance that he's become part of the ongoing political background of Starfleet. Jellico and Cox (as Jellico's voice) turned up in the animated series "Star Trek: Prodigy." Jellico, making his triumphant return as an admiral, assumes a small but important role in the ultimate fate of the experimental Protostar.

Bruce Maddox

"The Measure of a Man" is a stellar episode about the value of humanity, dignity, and individuality, as Data's worth as a person is challenged in court. But to succeed, it needs its hate sink. That's Bruce Maddox (Brian Brophy), an arrogant cyberneticist so convinced that he can dismantle Data and create make an army of new Datas that he convinces Starfleet to sign off on forcing Data into his service.

It doesn't help Maddox's likability that he's the only person to initially argue against Data joining Starfleet in the first place, saying that Data wasn't a sentient being. As the episode opens, he hasn't changed his tune. Maddox continually calls Data "it," which hurts. It's not a shock to us when Guinan later draws a direct line between Maddox's rhetoric and the history of slavery. Maddox, meanwhile, stumbles by being unable to quantify what sentient life means in a universe already so complex and strange. Brophy carries the bastard-ry of his character well, even showing, subtly, by the episode's conclusion, how one can outgrow their biases. By the time of "Picard," a recast Maddox (John Ales) figures prominently in the fate of a secret colony of androids.

Dathon

What could have been a goofy episode was made perfect by its guest star. Paul Winfield, a genre veteran who appeared in everything from "The Terminator" to "Babylon 5" to, of course, "Star Trek II: The Wrath of Khan," before he died in 2004, appears in "Darmok" as a Tamarian named Dathon. His culture speaks only in allegories, verbal hieroglyphs drawn from the epic of "Darmok and Jalad," and other Tamarian legends.

Winfield purposefully renders Dathon with no campiness and no hoary language barrier jokes. Dathon's purpose in trying to reach Picard despite the linguistic obstacles between them is deadly serious. Dathon is so stoic because he's eager to succeed. He softens when Picard begins to understand his language structure, using the "Epic of Gilgamesh" to show he's getting it. Dathon later dies happy, with the understanding that he's accomplished what no other Tamarian could — create a bridge with a new world. It's the Starfleet ethos, from the other side. It's telling that Dathon's legacy isn't a punchline when a Tamarian joins the cheeky "Lower Decks" crew. Kayshon can be funny, and his translator program is still working through some issues. But more importantly, the trustworthy Kayshon, instantly a beloved part of the cast, is the direct result of Dathon's efforts.

Admiral Norah Satie

Jean Simmons was a darling of old Hollywood, and in the '80s, she enjoyed a career resurgence thanks to some of the biggest TV movie events of the era, like "The Thorn Birds" and "North & South." It's the latter that led to her to cross paths with Jonathan Frakes, and he was delighted to work with her again on "The Drumhead," which he directed. It even turned out that Simmons was a secret Trekkie!

As Admiral Norah Satie, Simmons brings her fierce, undated pride to bear. Unfortunately, Satie is a fanatic in the Joseph McCarthy mode, and she's determined to find Captain Picard guilty of something treasonous by the time she's through with him. Like Bruce Maddox, Satie is an unforgettable character, but not because she's lovable. Worse, she only becomes more unhinged by the end, proving the lack of rationality that fuels these hateful movements. Simmons, as Satie, may feel a little theatrical. But in today's paranoid political environment, with many people feeling that hypocrites are once again driving violence toward minorities, it still feels all too real.

Eline

"The Inner Light" is one of Sir Patrick Stewart's finest hours, a Hugo-winning, tour-de-force episode that inserts Picard into the bittersweet lifetime of a dying world's lonely ambassador. "It was all a dream" can be a bad trope in fumbling hands, but for Picard, it was never just a dream. Nor for the audience. The life of Kamin stays with Picard throughout the series (and beyond) afterward, along with the flute he learned to play. But he doesn't carry the episode by himself, and Margot Rose, as his wife Eline, is often overlooked when kudos are handed out.

Eline is Kamin's pillar, always at his side as Picard adjusts to a world that pays no heed to his confusion. She's comforting, loving, and part of a life of loss. But it's her final speech that ties Picard/Kamin's lifetime of experience together. It's her voice that gently pleads with him to remember a people who had no chance to save themselves, and thus, can survive only in memory (and a simple flute). This may be Picard's pedestal, but it's Eline that holds it steady for him and Rose's heartrending performance that enables it to stand the test of time.

Amanda Rogers

There are few ways to go toe-to-toe in a battle of personality with John de Lancie as Q and come out the victor. The only method that sort of works is to be his straight man, unflappable and mildly annoyed. It usually works for Picard. But in "True Q," Amanda Rogers (Olivia d'Abo) finds another way to deal with a Q. Teenage sturdiness and flexibility combine with a lifetime of purely human caring. It's just enough to help Amanda hold her own with him.

Amanda is a sweet kid, and her few dips into temptation don't thrill her the way Q hoped. She's unable to commit to swaying the much older Riker into loving her, realizing that not even her powers can make something true when she deep down knows it's a lie. Eventually, Amanda accepts that she is, in fact, part of the Q Continuum, and heads off to join the omnipotent society. But with her goes all the morality and kindness she learned as a human. It's a shame we don't know how much of an effect the new young Q had on her peers. But since the Q we've all known and loved has gone through some big changes since then, it's possible she did engender a lasting change within the Continuum after all.

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