Longtime Star Trek fans each have their own fond memories of the show, both for good reasons as well as bad. In fact, some of the most memorable scenes in the franchise are also the most frightening and unnerving, and re-watching old episodes can make the hairs on the back of the neck stand on end.

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Throughout the various Star Trek TV shows, spinoffs and movies, there are a bunch of scenes that make many viewers nervous during a re-watch, even to this day. Here are ten of the most spine-tingling, in no particular order, proving that Star Trek's galaxy isn't all sunshine and rainbows—in fact, given its deep-space setting, pretty much none of it is.

The Exploding Enterprise (Star Trek III: The Search For Spock)

The Enterprise explodes

Star Trek fans were shocked to see their beloved Enterprise blown up in the lackluster third feature film. It came hot on the heels of a very dark storyline that involved Kirk's son David being knifed in the stomach by a Klingon warrior. When they demanded Kirk's surrender and moved for the Enterprise to be boarded, he agreed to their terms... kind of.

Before abandoning the Enterprise to beam down to the Genesis planet, Kirk set the ship's self-destruct mechanism. The Klingon boarding party beamed onto the ship just in time to be part of an incredible explosion that sent Trekker's favorite ship hurling across the horizon in a smoking fireball.

Borg On The Enterprise (Star Trek: First Contact)

The Borg assimilate the crew

The Borg were a natural enemy for Picard and his crew to battle in a Hollywood film, which is why they were chosen for First Contact. After the Borg initiate a second attack on Earth, their plans are thwarted when Picard joins the fight and uses his knowledge of their technology to exploit a key weakness.

It isn't enough to stop them permanently, however. Before being destroyed, the remaining Borg beam onto the Enterprise-E and begin transforming it from the inside out. When the crew learns of this, they venture into the dark bowels of the ship to face their enemy head-on. The tension is ratcheted up to unbearable levels, before the big reveal.

Peaceful Coexistence (Star Trek: The Next Generation)

Commander Remmick

Star Trek fans never saw this one coming. Season one came to a close with Picard facing down a conspiracy that threatened to take down the Federation from the inside. The culprit was a tiny parasitic alien species capable of taking over the minds of the bodies it attached itself to. With Starfleet's Elite infected, Picard and Riker launched one last-ditch plan to turn the tide.

They encountered the Mother parasite lurking inside the body of Commander Remmick, a previous antagonist. Without hesitating, Picard and Riker fired upon him, causing his head to explode, and his chest to melt away and reveal the parasite within. Even today, viewers still get nervous right before this gore-fest plays out.

Remembering The Room (Star Trek: The Next Generation)

The Holodeck

One of the creepiest and most disturbing stories in Star Trek lore is undoubtedly "Schisms" from the show's sixth season. The story centered on a crew undergoing weird physical and psychological traumas, all linked with a lack of sleep. When Doctor Crusher discovers that Riker's arm has been severed and reattached, she realizes there's a foul element at work.

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In an effort to locate their tormenters, several crew members enter a dark Holodeck where they try to piece together sights and sounds from their mentally suppressed experiences. The scene is so horrifying and frightening that it's impossible not to get chills even to this day.

Altovar Attacks (Star Trek: Deep Space Nine)

Altovar from Deep Space Nine

Dr. Bashir was the central figure in a frightening episode based entirely in his unconscious mind in the Deep Space Nine season three episode "Distant Voices." The story revolves around Bashir undergoing a telepathic assault by a fearsome-looking Lethean named Altovar after he was caught trying to steal a cache of bio-mimetic gel.

Inside Bashir's mind, Altovar stalked him through the station with the intent to murder him. A frightening scene takes place in a hallway when the lights begin to go out, prompting Bashir to take refuge in a turbolift. The doors almost manage to close before Altovar grabs them, forcing Bashir to kick his hand and force the doors shut. Believing he was safe, Bashir was shocked to hear Altovar trying to punch his way through the turbolift ceiling, which was especially scary.

Zombified Vulcans (Star Trek: Enterprise)

Zombie Vulcan

The controversial Star Trek: Enterprise took a page from George Romero's Living Dead films as inspiration for the season three episode "Impulse" which featured a derelict Vulcan ship with a horrifying mystery just waiting to be uncovered. It's known as one of the scarier Star Trek episodes in the entire franchise.

Fans of the episode still undoubtedly get goosebumps when T'Pol and Archer force open a door and nearly lose their heads to a zombified Vulcan swinging a weapon. It's an effective jump scare that paves the way for an entire episode centering around crazed Vulcans driven mad by exposure to Trellium, a substance toxic to their race.

The Borg Invade Federation Space (Star Trek: The Next Generation)

Picard vs. The Borg

Few Star Trek scenes are as tense and unsettling as this classic scene that took place during the final episode of season three. The Federation knew of the Borg's incursion into Earth for some time, but that gave them almost no options. Fans, on the other hand, bit their nails after seeing how the Borg mopped the floor with the Enterprise in season two.

This time, the Borg were on a mission to assimilate Earth and destroy the Federation. The buildup was tense and gradual until that pivotal moment when the Borg Cube is magnified on the Enterprise's main viewer. Even after repeated viewings, Trekkers still hold out hope that a different ship will pop up, instead.

Spider Barclay (Star Trek: The Next Generation)

Picard & Spider-Barclay

One of the most clever Star Trek episodes was the TNG episode "Genesis," directed by Dr. Beverly Crusher actress Gates McFadden. It is memorable for scenes depicting the crew of the Enterprise de-evolving to primordial states after a genetic virus is accidentally unleashed on the ship.

While much of the episode is eerie, ominous, and nerve-wracking, the tension reaches explosive levels when Picard is attacked through a pane of glass by Lieutenant Barclay, who is de-evolving into a gigantic spider. Arachnophobes must have severe trouble coping with this episode.

The Morgue Scene (Star Trek: The Next Generation)

Beverly Crusher hallucinating

Few Star Trek scenes are as terrifying as the infamous morgue scene from the season four episode "Night Terrors." The episode attempts to paint a picture of what happens when humans are deprived of R.E.M. sleep while simultaneously being assailed by an alien force lurking in the darkness.

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Dr. Crusher experiences the fright of her life when she's left alone in the ship's morgue, only to hear stirrings behind her. When she looks up, all the corpses in the room are sitting up, which is about as terrifying a thought as one could imagine. Fortunately, it was all in her head.

Khan's Mind Control (Star Trek II: The Wrath Of Khan)

Chekov & The Parasite

Many Trekkers are still forced to look away during the infamous ear-worm scene in the legendary Wrath of Khan. It's one of the titular villain's dastardly devices that he uses for the purpose of mind control, and he tests out two of them on Chekov and Captain Terrell, with horrible results.

It's hard to watch an up-close shot of anything crawling into one's inner ear canal, and, since there's an eardrum to burst through—among other things— in order for the creature to reach the brain's cerebral cortex, the resulting screams of agony are reason enough for anyone to clap their hands to their ears and shut their eyes tight.

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