When people think of the greatest villains in science fiction, most go for obvious answers like Darth Vader or the Xenomorphs. Villains within the popular genre tend to be frightening, manipulative, or just plain scary with their nefarious methods. However, people should not rule out the antagonists found in sci-fi stories on the small screen.

Any engaging sci-fi show needs an intimidating villain that will thwart the hero's plans and can even become the show's standout character. From Ben Linus from Lost to Vecna from Stranger Things, these sci-fi villains of the small screen leave a monumental impact on the viewers.

RELATED: The 10 Best Sci-Fi Movie Villains, Ranked

10 Sylar (Heroes)

Zachary Quinto as Sylar in Heroes

Every great hero like Peter Petrelli or Hiro Nakamura needs an equally formidable villain, and that is precisely what Sylar, played by Zachary Quinto, brings to the table. Originally gifted with "intuitive aptitude," he quickly discovers that he is capable of more than that after killing a man with telekinetic powers. From there, he becomes a super-powered killer who gains the abilities of his victims.

As the main antagonist of Heroes' breakout season, Sylar was an overpowered force to be reckoned with for the titular characters, making him a villain worthy of a comic book. Even though Heroes' four-season run had its ups and downs, there is no denying that those who stuck around were entranced by Sylar's presence.

9 Brother Day (Foundation)

Brother Day, played by Lee Pace, displays his power in Foundation

Apple TV's Foundation acts as ambitious sci-fi storytelling, and part of that comes from the main villain Brother Day, one of three rulers of the Empire. Cloned from the Empire's original ruler Cleon I, Day is the middle of the three rulers alongside the younger Dawn and older Dusk. However, he stands out among the three because of his desire to keep his reign alive.

Brother Day is willing to put on public executions, destroy entire worlds, and silently wipe out anyone who disrupts his vision of perfection and place of power. Lee Pace's magnetic performance and Foundation's poetic writing make him a villain to watch with each passing episode.

RELATED: 10 Greatest Sci-Fi Villains Without A Conscience

8 Harmony Cobel (Severance)

Patricia Arquette as Harmony Cobel in Severance

Another sci-fi hit from Apple TV+, Severance showcases a future where people can undergo a procedure that can surgically divide their work and home life. Overseeing this operation is Harmony Cobel, played by Oscar-winner Patricia Arquette, who monitors her employees so that they don't step out of line at Lumon Industries.

When the employees grow more suspicious and questionable about Lumon's primary goal, Harmony becomes insistent on punishing them by restricting their access to other work areas and putting them through rigorous tests to get them back on track. Combined with her furious temper and the clingy beliefs of Lumon's creator Kier Eagan, she is frightening for any viewer who can relate to having a mean boss.

7 The Man in Black (Westworld)

The Man in Black rides his horse and readies for a fight in Westworld

HBO's Westworld imagines a future where robot-populated theme parks exist, and the hosts eventually begin to rebel against their creators. However, no other character is more mysterious than the Man in Black, played brilliantly by Ed Harris. His presence will have viewers questioning whether he is a human or a host.

As Westworld unravels the perplexing identity of the Man in Black, his violent methods of killing and torturing hosts, whether they are civilians or violent gunmen, show how far he will go to find the answers to his questions about the titular park. Sporting a memorable all-black look and an overtaking sense of paranoia, he is an antagonist worthy of the addictive puzzle that is Westworld.

6 Moff Gideon (The Mandalorian)

Moff Gideon leads his army to a standoff in The Mandalorian

The Mandalorian gifted Star Wars fans one of the franchise's best characters in the titular bounty hunter. But his primary foe, Moff Gideon, also deserves equal recognition. Even with a late introduction in Season 1, his first entrance and lines of dialogue left fans wanting more from this villain.

Much like Gus Fring from Breaking Bad, Giancarlo Esposito made for an enthralling villain in The Mandalorian, sporting slick armor and a Darksaber as his weapon. Seasons 2 and 3 saw him become deadset on extracting fan-favorite Grogu's blood and creating a clone army to achieve galaxy domination. Moff Gideon became another prime example that Esposito has a knack for playing fantastic villains.

RELATED: 10 Ways Moff Gideon Is The Best Star Wars Villain

5 Darth Maul (Star Wars: The Clone Wars)

A furious Darth Maul wields his lightsaber in Star Wars: The Clone Wars

When Darth Maul made his introduction (and exit) in The Phantom Menace back in 1999, no one was prepared for his eventual return several years later. The Clone Wars had a plethora of great villains throughout its run, but none were as engaging or exciting as this resurrected Sith.

Discovered by Savage Opress at the end of Season 4, Maul returned with a renewed vengeance to hunt down Obi-Wan Kenobi. His return also ignited some of The Clone Wars' most memorable story arcs including Season 5's "Shadow Collective" where he fought his former master Palpatine and Season 7's "The Seige of Mandalore" where he dueled Ahsoka Tano.

4 Silco (Arcane)

Silco presents his scarred appearance in Arcane

Netflix's Arcane caught tuned-in viewers off guard thanks to its beautiful animation, intriguing lore, and well-constructed characters, especially antagonist Silco. Residing in Zaun, an underground and polluted city, Silco provides ruthlessness and a desire for power as he overrules the citizens and sells experimental drugs.

Silco is manipulative towards characters like Jinx and Marcus, violent and intelligent when confronting opposers like the Chem-Barons, and terrifying to look at due to his physical scars. Along with these traits, his sharp dialogue and committed voice acting by Jason Spisak make him an unforgettable antagonist for a show as well-crafted as Arcane.

3 Ben Linus (Lost)

Michael Emerson as Ben Linus in Lost

Lost was the water cooler show of the 2000s that left viewers curious about what would happen next to the Oceanic Flight 815 survivors. Things escalated further with the introduction of Ben Linus, one of the show's most complex characters. Introduced in the back half of Season 2, he soon became a major threat to the survivors.

As the leader of the Others, Ben is a strategic mastermind who always has a plan. He aids in kidnapping Walt just so he can get prisoners in exchange, manipulates imprisoned characters Kate and Sawyer against Jack, and constantly makes the selfish choice of preventing everyone from leaving the island for his own benefit. His strategies present how dedicated he is to protecting both the mysterious island and his fellow Others. While he grew into an anti-villain as time went on, Michael Emerson's Emmy-winning performance still made viewers love to hate the character.

RELATED: Lost: 10 Most Important Characters From The Show

2 Homelander (The Boys)

Antony Starr as Homelander on The Boys

In the world of The Boys, superheroes are treated as celebrities but are actually terrible people inside. However, the worst of them all is also the most powerful. Homelander, leader of the Seven, may seem like a Superman-type savior, but he is more twisted behind the scenes. His powers of laser vision, invulnerability, and flight make him an indestructible weapon, and each episode has him prime to snap at any second.

Homelander cruelly laughs at his killings, threatens to laser anyone who upsets him, and struggles to fight his insecurities. Every character on The Boys gets their time to shine, but Homelander significantly stands out above them all due in large part to Antony Starr's dedicated and award-worthy performance.

1 Vecna (Stranger Things)

Jamie Campbell Bower as Vecna in Netflix's Stranger Things

Stranger Things contains several deadly and disgusting creatures from the Upside Down that terrorize the town of Hawkins, Indiana. Each season has the citizens battling a new yet similar threat. However, Season 4 has introduced Stranger Things' most horrifying villain. Unlike the previous threats from the Upside Down, Vecna feels like Stranger Things' ultimate big bad.

Vecna curses his victims by feeding into their trauma and disturbingly slaughtering them in an attempt to escape and bring destruction to the world above. Plus, his backstory showcases his grudge against fan-favorite Eleven because she trapped him in the Upside Down, making him a grander and more personal threat. Jamie Campbell Bower is devilishly scary as the villain, and fans can't wait to see what he'll bring next.