Fans of the iconic, long-running "Doctor Who" can all agree on one thing -- a lot of strange aliens have appeared on the series since it started back in 1963. While most of the time, viewers are getting lost in the "wibbly-wobbly timey-wimey" parts of the show -- watching Peter Capaldi and Jenna Louise Coleman take on the Daleks, or Matt Smith, Karen Gillan, and Arthur Darvill try to mend the crack in the universe -- the aliens on "Doctor Who" are an entertaining mainstay.
It doesn't matter which of the 12 Doctors is your favorite, since there's no denying that the aliens help keep the tension alive and the show intriguing. Sure, there are some human-looking species, like the Time Lords, but the writers and special effects designers continue to go bigger and get stranger. Case in point -- these six creepy, crawly, mind-boggling aliens.
Viewers met this species during David Tennant's time as the Tenth Doctor in the episode "Love & Monsters." The Abzorbaloff does as its name says and consumes people by absorbing them. While the species is incredibly unsettling, there's a fun fact about its inception: A 9-year-old named William Grantham designed the alien, and it was used in the show after he won a contest. He did a great job -- the boy succeeded in creeping out just about everyone who watched the episode.
Popping up during the Eleventh Doctor's reign and proving they're in it for the long haul, the Silence are among the creepiest aliens around, because the characters who come into contact with them later forget them completely. A good thing, though, since they look like the personified mask from "Scream" with its mouth removed -- and a thousand times scarier. Thankfully, Amy Pond, Rory, and the Doctor overcame the Silence, eventually. Just be on the lookout for any stray tally marks on your body -- a sure sign you've come in contact with one, but you've forgotten about it.
This species of "Doctor Who" aliens first came about in the original series way back in 1975 and they've made quite the impression ever since. The Zygons can replicate another human being as long as that person is still alive, which is good, because in their natural form, the species are basically octopus tentacles who can walk and talk. This alien made its triumphant return to modern-day, or Nu-Who, in "The Day of the Doctor," which celebrated the show's 50th anniversary, coming back to scare a whole new generation of fans.
The Adipose may be among the cutest alien species in "Doctor Who," but don't let that fool you. When the Tenth Doctor and Donna Noble, played by Catherine Tate, discover the adorable species, they eventually find out the little critters are composed of -- wait for it -- human fat. Gross. If you can forget that small fact, then sure, they're the most adorable aliens around.
Ahh ... a species of walking potatoes -- that's what the Sontarans look like. They're essentially pint-sized walking, talking spuds that only think about war. To be fair, their world values military smarts above all else. They regard discipline and honor as the two best virtues, but it's their appearance that's most unsettling -- especially since they only have three fingers on each hand. Military smarts plus potato plus three fingers equals a majorly eerie alien species.
Lady Cassandra O'Brien
Including Lady Cassandra O'Brien on this list is kind of cheating, because technically, she's a human. However, when Rose Tyler (Billie Piper) and viewers meet Lady Cassandra, she is the last "pure" human, which has resulted in her using any means she can to stay alive. Instead of being a walking, talking, breathing woman, she's a flat, amorphous face that has been stretched thin and needs to be "moisturized" by her minions as much as possible. Even though she's human, Lady Cassandra embodies creepiness to the umpteenth degree.