If you're new to the Whoniverse, though, you'll need a crash course in Who-speak before you go adventuring. Here are 12 terms to get you started:
The TARDIS, aka Time and Relative Dimension in Space, is the Doctor's one-of-a-kind combination spaceship and time machine. It can fly anywhere and anywhen, occasionally read the Doctor's mind, and even morph into a human brunette named Sexy (but just the once).
Also, because its “chameleon circuit” is busted, it's no longer able to blend into its surroundings, but is instead stuck, for the most part, in the form of a blue 1960s-style London police box. However, the TARDIS is famously much bigger on the inside.
Where would be the Doctor be without his companions? In the bottom of a galactic volcano, probably.
Part audience surrogate, part moral compass, and part 'straight-woman' to the Doctor's kooky comedy (i.e. the Bert to his Ernie), companions are regular humans who accompany the Doctor on his adventures in space and time. While companions tend to be attractive young women (showrunner Steve Moffat has an iffy explanation as to why that is), there’s never any real hanky-panky.
The Doctor's had many fine companions, though once you've caught up on a couple seasons, you'll likely be partial to Donna Noble, we think (Amy Pond is a close second).
3. TIME LORD
The Doctor certainly looks human (but still not a ginger), but he’s actually a Time Lord from the planet Gallifrey. Time Lords have a variety of extraordinary powers, including telepathy, the ability to understand various languages (including those of babies and animals), and physicial regeneration. The latter ability even lets these super-aliens generate new bodies (in the form of new actors) every few decades as needed--or, in human TV time, every couple of years--and live well into their 900s at least.
The planet Gallifrey was thought to have been destroyed in the Last Great Time War, a deadly conflict between the Time Lords and their archenemies, the Daleks. However, the planet was eventually found to be caught in a "pocket universe," and has since been revisited in the show.
Where the name Gallifrey comes from isn't clear, but fans of the show have come up with some possible connections. For example, the word is reminiscent of gallimaufry, meaning 'medley or hodgepodge,' which comes from the French galimafrée, a word for 'hash,' or 'ragout.' Galimafrée, too, could be a combination of the Old French galer (to make merry) and the Old North French mafrer (to eat a lot).
The Daleks, i.e. the Doctor's main nemeses, are machine on the outside but alien on the inside, and say “EXTERMINATE!” a lot. First introduced in 1963, Daleks were originally hilariously low-tech and got an upgrade in 2005 for the series reboot, but they still retain their fundamental qualities (like plunger-shaped appendages).
As for their race's name: in a 1964 interview, show writer Terry Nation claimed that the inspiration for the word Dalek came from seeing an encyclopedia with DAL-LEK on its spine. Then, in 1973, he admitted that the word “simply rolled off the typewriter.” However, linguist Ben Zimmer points out that in Serb-Croation dalek can mean “distant,” and by extension, “alien.”
The Cybermen of Mondas started out as humanoid; however, once they started implanting artificial body parts, they just couldn’t stop. Now they’re almost all robot—cold, calculating, and hell-bent on making everyone else into Cybermen, too.
The word Cyberman is a Doctor Who-original, coined in a 1966 episode, but has since been widely adopted and now might refer to any cyborg or humanoid robot. The term had its own long history before its use on the show, however: the practice of attaching the prefix cyber- (relating to computers, technology, and anything futuristic) to other terms originated in the early 1960s with the shortening of cybernetics, first used in the 1940s to describe the new technology and theory of “self-regulatory control through feedback mechanisms.” And the word cybernetics was itself taken from the Greek kybernetes, or "steersman.”
A bulky, mostly humanoid warrior race from the planet Sontar, the Sontarans first made their appearance in 1973. They reproduce by cloning (hence their general alikeness), are crazy for both battle and glory, and have heads that're a bit like potatoes.
Whovian legend says the accepted pronunciation, son-TAR-an, is credited to Australian actor Kevin Lindsay, who played the classic character Sontaran Linx. The creature’s creator, show writer Robert Holmes, argued for a SON-tar-ran pronunciation, to which Lindsay (hopefully dressed as Linx) replied, "Well, I think it's ‘son-TAR-an’, and since I'm from the f**king place, I should know."
8. SONIC SCREWDRIVER
The sonic screwdriver is the Doctor’s tool of choice. First introduced in 1968, it was used only intermittently throughout the series 'til its 2005 reboot, when it came back full-force. As your classic all-purpose magic tool, the sonic screwdriver acts as a lockpicker, a cutting tool, a flashlight, a universal remote control, a diagnostic device, and much, much more.
The Torchwood Institute is a secret organization established by Queen Victoria in Doctor Who and which is tasked with defending the world against extraterrestrial and supernatural baddies—a tall order for an organization that employs no more than 10 people at a time. Torchwood is also a popular Doctor Who spinoff that centers on the shady (but heroic) group, and which features Doctor Who veteran character Jack Harkness, a dashing, (almost) immortal American who made his first appearance in a 2005 episode.
Torchwood—an anagram of "Doctor Who"—was the code name used, according to the BBC, “to disguise preview tapes of the first episodes” of the Doctor Who reboot in 2005.
10. BEHIND THE SOFA
The term behind the sofa refers to a television show so scary that one must hide "behind the sofa" in self-defense. It supposedly arose in the 1970s in reference to particularly frightening Doctor Who scenes, and was likely further popularized by a 1991 Doctor Who exhibit at London’s Museum of Moving Image called Behind the Sofa.
“People assume that time is a strict progression of cause to effect,” says the 10th Doctor in a 2007 episode. “But actually, from a nonlinear, non-subjective viewpoint, it's more like a big ball of wibbly-wobbly, timey-wimey ... stuff.” And, to be honest, timey-wimey and wibbly-wobbly pretty much sum up how time travel is explained in the show.
We have the Yanks to thank for this one. Whovian, referring to a Doctor Who fan, seems to have been coined in the early 1980s by the Doctor Who Fan Club of America, which published a newsletter called The Whovian Times. However, some fans dislike the name, deeming it too Seussian, and prefer Wholigan instead. So, if you think you're likely to become a Doctor Who fan in the near future, you might want to put some thought into which fandom name feels right for you.