In 1966, Star Trek first hit the airwaves and broke new ground for science fiction television. While it was canceled after three seasons, it was followed by Star Trek: The Animated Series and six feature films based on the original series. There have been four spin-off TV series that followed: Star Trek: The Next Generation, Star Trek: Deep Space Nine, Star Trek: Voyager and Star Trek: Enterprise. Star Trek: TNG picked up the torch with four more movies until the series was rebooted in 2009 with Star Trek, followed by two more movies in the new timeline: 2013's Star Trek Into Darkness and 2016's Star Trek Beyond.

RELATED: 15 Original Star Trek vs Abramsverse Star Trek Memes

That's a lot of material for one franchise, and since that's covered over 50 years and put hundreds of actors on the big and small screen, quite a few famous faces have passed through the Star Trek universe. While most of them are well-known, it's easy to see how a few actors might have slipped your memory. With the new Star Trek: Discovery TV series on CBS and the digital platform CBS All Access, CBR thought it was time to refresh your memory about some of the actors and celebrities on Star Trek you might have forgotten.

16 CHRIS HEMSWORTH

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Chris Hemsworth started out on an Australian soap opera before he hit it big in 2011 as the Norse god of thunder Thor in the Marvel Cinematic Universe. Before that, he had a brief but memorable cameo in 2009's Star Trek. The idea behind the Star Trek prequel he appeared in was that history had been changed from the timeline of the original series.

In the opening, we saw the Federation USS Kelvin encounter a Romulan ship that came out of a time portal from the future in search of Ambassador Spock. The ship attacked the Kelvin, and the first officer sacrificed himself to save the rest of the crew. That first officer was George Kirk, the father of James T. Kirk, and he was played by a less muscular (but still awesome) Chris Hemsworth.

15 KIRSTEN DUNST

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At the age of three, Kirsten Dunst started out modeling for TV commercials but got her big break with an acclaimed role as a young vampire in Interview With The Vampire in 1994. Since then, she became a star as Peter Parker's long-suffering love Mary Jane Watson in the Spider-Man trilogy. Yet you may not know or remember that one of her earliest roles was on the Star Trek: The Next Generation episode "Dark Page."

In 1994, the 11-year old Dunst was Hedril, a young alien girl whose race was trying to learn a spoken language because their native form of communication was telepathy. When Deanna Troi became overwhelmed by the psychic power of the aliens, she uncovered a painful memory her mother had repressed for years.

14 GABRIELLE UNION

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The talented and beautiful Gabrielle Monique Union was a model who moved onto acting, first getting attention with her supporting role in 1999's 10 Things I Hate About You. She continued her teen movies with Bring It On and romantic comedies like 2012's Think Like a Man. Most recently, she's been starring on Being Mary Jane, which began in 2013.

In 1997, season six of Star Trek: Deep Space Nine aired the episodes "Sons and Daughters" about Worf reuniting with his son Alexander aboard a Klingon vessel and finding their relationship strained. Union played a Klingon officer named N'Garen who was mocking Alexander in the ship's mess hall, which eventually turned into a fight. It was a small role and she wore heavy Klingon makeup so it was easy to miss.

13 TERI HATCHER

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Teri Hatcher is one of the rare actresses who scored roles in not one but two hit TV series. In 1993, she was Lois Lane, the co-star of Lois and Clark: The New Adventures of Superman, which was a major force in pop culture during the 1990s. In 2004, she hit TV gold again as Susan Meyer in the hit dramedy Desperate Housewives. She was also a Bond girl in Tomorrow Never Dies.

In 1988, Star Trek: The Next Generation aired "The Outrageous Okona" during the second season where a rogue captain drew the Enterprise into an intergalactic conflict. The transporter chief B.G. Robinson was Teri Hatcher. She flirted with the captain and beamed people around, but wasn't a major cast member. In fact, so much of her performance was cut that she asked her name to be left out of the credits.

12 KELSEY GRAMMER

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Kelsey Grammer is a classically trained actor who's been active for decades on television, movies and theater. Grammer is most widely known for his role as Dr. Frasier Crane on NBC's Cheers and a spin-off entitled Frasier, which won him both Emmy and Golden Globe awards.

Grammer also appeared briefly as Captain Morgan Bateson in the finale of Star Trek: The Next Generation's fifth season episode "Cause and Effect" in 1992. In the episode, the Enterprise encountered a distortion in space-time that caused the ship to be destroyed, creating a time loop where they kept reliving the events over and over again. When the crew was finally able to stop the loop, Grammer was the captain of the ship that kept coming out of the space distortion, destroying the Enterprise.

11 FAMKE JANSSEN

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When you think of Famke Janssen, the first thing that comes to mind is probably the psychic Jean Grey in the X-Men movies. You might also think of her role as Xenia Onatopp (one of James Bond's most arresting enemies) in the 1995 film GoldenEye, or her role as Ava Moore on the TV series Nip/Tuck. Janssen actually started out as a model until she turned to acting.

Her first professional acting role was as the seductive Kamala in the fifth season of Star Trek: The Next Generation in 1992. The episode "The Perfect Mate" was about Kamala, an alien empath who was being transported by the Enterprise to an intended wedding, but her power to change into the perfect mate for anyone she met captivated the crew. Janssen was also up for playing Jadzia Dax on Star Trek: Deep Space Nine, but turned down the role.

10 TOM HARDY

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Tom Hardy is the English actor who's setting Hollywood on fire right now, and has been for some time. He started out in supporting roles in movies like 2001's Black Hawk Down and 2010's Inception but became a superstar for his award-winning performance in the 2008 biopic, Bronson. From there, he was the super-strong villain Bane in 2012's The Dark Knight Rises and took over the role of Mad Max in 2015's Mad Max: Fury Road.

In 2002, Hardy played Shinzon in Star Trek: Nemesis as a younger clone of Jean-Luc Picard who took over the Romulan Empire and tried to destroy the Federation. He wore heavy makeup in the movie with a false nose and chin to make him look more like Patrick Stewart. While the movie wasn't very well-received, Hardy delivered a fierce and passionate performance.

9 SARAH SILVERMAN

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Sarah Silverman started out as a stand-up comedian until she became a writer and later performer on Saturday Night Live in 1993. She moved on to Mr. Show in 1995 and starred in her own 2007 sitcom, The Sarah Silverman Program. That and her other TV work earned her Emmy award nominations and two Emmy awards. She's also been in movies like 2003's School of Rock, Wreck-It Ralph (2012) and A Million Ways to Die in the West in 2014.

In 1996, the third season of Star Trek: Voyager brought in Sarah Silverman as Rain Robinson in the two-part episode "Future's End." Robinson was a modern-day scientist who picked up the warp signal of Voyager as part of the SETI program. She was almost hired as a regular cast member on Star Trek: Voyager, but the show went with Jeri Ryan instead.

8 SETH MACFARLANE

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Seth MacFarlane is best known as the creator of Fox’s TV series Family Guy, for which he also wrote and voiced many of the characters. After it was canceled, the show returned in 2005 and MacFarlane created two more animated series: American Dad! in 2005 and the Family Guy spin-off The Cleveland Show in 2009. In 2012, MacFarlane moved into movies by writing, directing, and starring in Ted (2012), Ted 2 (2015) and A Million Ways to Die in the West in 2014.

While Seth MacFarlane is currently on TV in the Star Trek homage/rip-off The Orville, there was a time when he was actually on the show itself. In the third season 2004 episode "The Forgotten," Star Trek: Enterprise introduced MacFarlane as an unnamed engineer. In the following year, MacFarlane returned in the episode "Affliction" and had a name this time: Ensign Rivers.

7 JASON ALEXANDER

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When we talk about Jason Alexander, it's impossible to avoid his role as George Costanza on the hit TV show Seinfeld. From 1990 until 1998, he was the co-star of the "show about nothing" that earned him nominations for Emmy and Golden Globes. Before and after that, Alexander had a long career on Broadway, movies and television.

Alexander was a longtime fan of Star Trek who wanted to play an alien on a Trek series. They offered him roles many times, but he turned them down because they were human and he wanted to be an alien. He finally got his wish in 1999's Star Trek: Voyager episode "Think Tank." He played Kurros, the leader of a group of highly intelligent (and arrogant) aliens who offered to help Voyager in exchange for taking Seven of Nine into their group.

6 THE ROCK

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Dwayne Johnson is one of the world's biggest movie stars right now. He started out as a football player before moving to professional wrestling as The Rock. His acting career in movies started with 2001's The Mummy Returns, then had a spin-off in The Scorpion King in 2002. He made other movies like 2004's Walking Tall and supporting roles in movies like 2008's Get Smart, but when he played Luke Hobbs in 2011's Fast Five, he really took off.

With Johnson dominating the big and small screen, it's easy to forget there was a time when he was just a popular wrestler. One of his first (scripted outside of the ring) acting roles was in 2000 on Star Trek: Voyager's sixth-season episode "Tsunkatse." Johnson played an alien wrestler who fought Seven of Nine in gladiatorial combat.

5 KIM CATTRALL

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Kim Cattrall started her film career in 1975's Rosebud with small roles in 1982's Porky's and 1986's Big Trouble in Little China. She broke out as a star in the surprise 1987 hit Mannequin, but she's best known as Samantha Jones on the hit series Sex and the City, which earned her five Emmy Award nominations, four Golden Globe Award nominations and a win in 2002's Golden Globe for Best Supporting Actress. She followed that up with two movie sequels, 2008's Sex in the City and Sex and the City 2 (2010).

Before all that, Cattrall was in Star Trek VI: The Undiscovered Country (1991) as the Enterprise's Vulcan helmsman Lt. Valeris. Valeris was Spock's protege until she betrayed them to assassinate the Klingon ambassador and was forced to undergo a Vulcan mind meld to get information on the plot.

4 ASHLEY JUDD

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Ashley Judd was best known for her mother and sister's country music act the Judds, but she made her mark in acting through a lot of high-profile movies like A Time To Kill (1996), Eye of the Beholder (1999), Divine Secrets of the Ya-Ya Sisterhood (2002), Where the Heart Is (2000), Kiss the Girls (1997), Double Jeopardy (1999), and (most recently) The Divergent Series: Insurgent in 2015. Yet her whole acting career started with Star Trek.

Judd's first professional acting role was in 1991 as Ensign Robin Lefler in Star Trek: The Next Generation's fifth season episode "Darmok" where she had a relationship with Wesley Crusher. She returned in the same season with "The Game" and was intended to be a recurring love interest for Crusher, but didn't return.

3 STEPHEN HAWKING

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As a theoretical physicist, Dr. Stephen Hawking transformed the world with his groundbreaking theory linking the theory of quantum mechanics and relativity. He was the Lucasian Professor of Mathematics at the University of Cambridge from 1979 to 2009 and wrote the best-selling book, A Brief History of Time. It's more remarkable that he did it while suffering a rare early-onset form of amyotrophic lateral sclerosis that left him paralyzed.

In the sixth season of Star Trek: The Next Generation, the 1993 episode "Descent" included a scene where Data created a program on the holodeck so he could play poker and chat with three of the greatest scientific minds in history: Albert Einstein, Sir Isaac Newton and Stephen Hawking. Not only was it a great moment to see him honored with his peers, but it was also the only person to date who's played themselves on Star Trek.

2 NIKKI COX

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There's no question that the 1995 TV show Unhappily Ever After's breakout star was Nikki Cox, the daughter of a dysfunctional family. Cox started acting when she was 10, making appearances on shows like Baywatch, Mama's Family and Blossom. She had a starring role on General Hospital starting in 1993 before she got her own sitcom Nikki starting in 2000 and played Mary Connell on 2003's TV show Las Vegas.

One of her first roles was on Star Trek: The Next Generation with the 1989 episode "Pen Pals," where Data makes contact with an alien girl (Cox) named Sarjenka, who is on a distant planet threatening to be destroyed. Since the planet is pre-warp, the Enterprise struggled with whether to break the Prime Directive to save her.

1 JOHN TESH

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In 1989, Star Trek: The Next Generation's second season aired "The Icarus Factor." While the main story was about Commander Riker trying to decide if he should accept command of his own starship and dealing with his estranged father, the subplot was about Worf's Klingon identity. Crusher, La Forge and Data discovered that Worf was upset that he wouldn't be able to go through an important Klingon ritual.

To help Worf, the crew created a holographic simulation in the holodeck where Worf passed through a gauntlet of Klingon warriors while reciting vows and being jabbed with "pain sticks." You'd be forgiven for not recognizing one of those holographic Klingons as musician and host of Entertainment Tonight, John Tesh. Apparently, he had stopped by the set for a segment and accepted the offer to join the cast.

Who's your favorite guest star in Star Trek? Let us know in the comments!