Science-fiction television often explores profound themes of existence through the prisms of science, technology and the otherworldly. But sometimes the programs just want to scare your socks off.
Here is a rundown of some of the most frightening and disturbing sci-fi series that have ever appeared on TV and what it is that makes them so hair-raisingly entertaining.
"The Outer Limits"
"There is nothing wrong with your television set. Do not attempt to adjust the picture. We are controlling transmission ..." This voice-over began many episodes of "The Outer Limits" when the anthology series ran for 49 episodes from 1963 to 1965. A second series aired from 1995 through 2002. The original featured a host of ugly monsters, aliens and sci-fi settings such as Mars, and tropes such as time travel; the second had its share of grotesque beings as well, and featured stories by sci-fi luminaries including Harlan Ellison and A. E. van Vogt and by horror master Stephen King.
"The Walking Dead"
This first-year AMC series began freaking out TV audiences as soon as it premiered, appropriately enough, on Halloween. A ragtag group fights for survival in a zombie-infested landscape and sees its fair share of guts and gore in the process. The real-life Centers for Disease Control and Prevention in Atlanta figured prominently in the show's first season, in which a scientist tries to find out what caused the outbreak of the undead. The second season is on the way; if the TV show remains close to the comic book on which it is based, plenty of scariness lies ahead.
The Cylons – machines that can look like people or like chrome-skinned, clanking, murderous robots — have launched a surprise attack and nuked the Twelve Colonies of Man. The apocalypse annihilates all but 50,000 or so human survivors, who are scattered aboard several spacecraft with but one aging warship –— the Battlestar Galactica — left to protect them. And, oh yeah, the Cylons mean to finish what they started, and they have already infiltrated the remaining band of humans. Scared yet? This SyFy series (the reworking of a 1978 TV series that lasted one season) earned critical acclaim and has launched a number of spinoffs. [5 Reasons to Fear Robots]
This campy series pushed the envelope for daytime television back in 1966 when it first aired. Witches and warlocks, as well as vampires, werewolves, ghosts and other monsters, inhabited this gothic soap opera. Sci-fi staples of time travel and a parallel universe also made their way into the melodrama, which racked up an impressive 1,225 episodes before it ended in 1971. A prime-time remake in 1991 never got legs; a feature film involving Tim Burton and Johnny Depp is said to be in the works.
Who knew whistling could sound so ominous? From the iconic opening theme music onward, this program intrigued and frightened audiences in equal parts over its long run from 1993 to 2002. FBI agents Fox Mulder and Dana Scully chased down many "monsters of the week" — from body-controlling Arctic worms to hallucinogenic spore-producing, human-eating fungi — as well as people who had extraordinary powers such as pyrokinesis (abilities related to igniting fires) and invisibility. Extraterrestrials played an increasingly huge role as the narrative arc unfolded.
In many ways the successor to "The X-Files," this show also chronicles FBI agents – this time in the Bureau's "Fringe Division" — as they chase down bizarre occurrences and crimes. "Fringe" has now expanded into a whole parallel universe, and all sorts of disconcerting events and issues have been raised, from scaring people to death (complete with psychosomatic stigmata) to the stealing of human heads by other-dimensional shape-shifters. Fringe, indeed.
After a 1983-84 miniseries, "V" began airing as a one-hour weekly show in October 1984, though the program would not last six months. (A re-imagined "V" returned to the small screen in 2009.) Aliens intent on taking over the Earth tried to kill and trick their way to domination in the face of a resistance movement of humans and rebel aliens. The short-lived show dealt with a city-destroying super-weapon, biological warfare and lots of malevolent deception, among other distressing topics.
From "The X-Files" creator Chris Carter came this 1996-99 show following a profiler who had the freaky ability to channel the visions of murderers. Frank Black did the odd job for a secret society known as the Millennium Group, which as the series unfolds was revealed to be a sinister, centuries-old organization rather than a modern-day law enforcement group mostly staffed by FBI agents. Gruesomeness, psychic visions and religion-steeped conspiracies combined to give this show an all-around unnerving edge.
"The Twilight Zone"
The nightmarish theme music, introduced in the original series' second season in 1960, is probably playing in your head as you read this. "The Twilight Zone" original series in the late 1950s and early 1960s spawned two more TV series as well as a movie, comic books, games and much more, including a Walt Disney theme-park ride. But don't let all that apparent mirth mislead you: The anthology series created by Rod Serling harbored some seriously creepy stuff. An example: In one episode a young William Shatner played a newly released sanitarium patient who alone kept seeing a Yeti-like monster on the wing of the plane he was in. In another called "The Eye of the Beholder" (spoiler alert!), a woman underwent rounds of cosmetic surgery to try to look like everyone else, who turned out to have disfigured faces.
"Terminator: The Sarah Connor Chronicles"
This 2008 spinoff from the four-films-and-counting franchise garnered fan and critical praise, yet lasted only 31 episodes before meeting its own apocalypse. The series explored the "Terminator" wars of man versus machine that were being waged increasingly through time travel, as each side tried to position itself for the day when the nukes inevitably would fall. Sarah Connor worked to protect her son John (the future leader of mankind) against multiple assassination attempts; his new robotic bodyguard, Cameron, was as chilling as she was beautiful. The occasional "Terminator of the week" was scary enough, but it was the pervading sense of impending doom that made this show memorably haunting.
Sign up for the Live Science daily newsletter now
Get the world’s most fascinating discoveries delivered straight to your inbox.