The series follows Russell Wright (Mark Rendall), a 12-year-old boy who's recently moved into a new house. When his family first arrives, Russell sees a something strange in one of the windows. When he goes to the corresponding room, he finds a bed, where the strange thing ducks under. Russell follows it, and finds himself crawling through a tunnel to the bizarre and magical land of Under, where he is then crowned the new king.
Unfortunately, not everyone is too happy with this. In particular, Bob Wire (Cal Dodd), the guy who was acting as king until a new one arrived. He wants the crown back, and he won't rest until it sits atop his head again. There's also Cliff (Robert Tinkler), a local bully who was the previous ruler of Under, and doesn't like that Russell took that from him, as well as Auntie First (Marnie McPhail), the despotic ruler of Near Under who is accompanied by her gentlemanly right-hand man Captain Darling (James Kee).
Thankfully, Russell isn't alone. With the help of his royal court, consisting of Vernon the android (Robert Tinkler) and Loopy the jester (Adam Reid); the Ex-Princess of Near Under, Populah (Julie Lemieux); and Gus (James Kee), Russell's dog who followed him into Under (and can talk down there), Russell navigates the ins and outs of being a king, goes on adventures all throughout Under, and does all he can to keep Bob Wire, and other enemies of Under, from taking the crown.
The series aired on Family Channel from 2003 to 2005 for 52 episodes over 2 seasons.
King contains examples of:
- A Child Shall Lead Them: Under's ruler is whoever enters through the portal above the king's throne. Under's had numerous kings before Russell, all of them kids.note
- Alliterative Name: It is unknown if it is her real name but we have 's Princess Popular.
- Bottomless Pits: The Clockmaker moves into one in "The Monster Who Wouldn't Arrive". Loopy describes it as the hottest new lifestyle choice.
- The Bully: Cliff, the previous king of Under. He targets Russell specifically because Russell is the new king.
- Catchphrase: Russell has one, "Yonkers!", and Bob Wire has a habit of calling people "Schmeds".
- Cloud Cuckooland: Under is this, being inhabited by all manner of weird and wacky creatures.
- Extra Eyes: The Krenits from "Slow Plums And Krenits" have eyes all over their heads.
- Eye on a Stalk: A number of beings in Under have their eyes on stalks.
- God Save Us from the Queen!: Auntie First, the ruler of Near Under, is a despotic tyrant. In her first episode, she forced everyone to vote no on letting all the pets in Near Under go free. When she discovered Russell voted yes on that, she kicked him out of Near Under.
- Instrumental Theme Tune: Outside of Russell's narration, the opening theme is a completely instrumental, ska-influenced theme song, devoid of any lyrics. The French dub, in comparison, lacks Russell's narration, turning the opening purely into this.
- Laser-Guided Amnesia: Russell suffers this in "A Glass Of Memory", upon falling into the "GeeIForget River".note
- Logic Bomb: In "Brain Jam", Vernon's mind locks up and he reverts to telling time when asked a riddle.note He finally snaps out of it upon hearing the answer.note
- Mooks: Bob Wire relies on little green toad-like critters called Frags to help him do his dirty work.
- One-Word Title:
- King, naturally.
- The title for the French dub averts this, being retitled to "Le roi, c'est moi" ("The king is me").
- Plant Person: The Florians. They communicate through smells and bursts of pollen.
- Precision F-Strike: Or at least as close to the F-bomb as a kids show can allow. Bob uses the word "freaking" on a couple of occasions, namely in the episodes "King Russell the Repellent" and "As Good As Gus", among others.
- Punny Name: Bob Wire. Like barbed wire, which is fitting since that's what Bob Wire is.
- Ridiculously Human Robot: Vernon. He's a robot who moves around on wheel feet, but has a personality, is able to think up all kinds of wacky things, and has the ability to eat.
- Sapient House: The Tower Of Derision in its titular episode. It's a tower where a face manifests on the walls to whoever tries to climb it, and proceeds to hurl insults at them until they can no longer take it, and run out in tears.
- The Scapegoat: This trope is Invoked on the Pubrick in "Never Be Nice To A Pubrick". When Russell makes a law forbidding people from blaming the Pubrick on stuff, he learns the hard way that Pubricks turn into giant monsters when they're not being blamed for everything.
- Stumbled Into the Plot: Russel Wright finds a portal hidden under his bed and discovers a land called Under, where he is deemed king because he's from "the place where kings come from" (our world).
- Taken for Granite: The Great Big Hairy Eyeball in "Blizzard in a Box" temporarily turns anyone it looks at to stone.
- Talking Animal: Any animal that comes from Up to Under gains the ability to speak. Gus is the most prominent example, as he's one of the main characters.
- The Tooth Hurts: In "Monsteritis", monster Loopy bites Vernon on the arm, which just shatters his teeth.
- Ungrateful Bastard: Near Under is a kingdom full of them. When the people of Near Under seek asylum in Under, Vernon builds them all a place they can live in, only for them to complain about it. They also come running back to Near Under when Auntie First and Captain Darling start singing Near Under's anthem. Ex-Princess Populah cites this as the reason why she let Auntie First have the throne.
- Vanishing Village: The Uncertain City in "Monsteritis", which constantly flickers in and out of existence. Whenever it vanishes, whoever is inside it vanishes as well, and won't return until the Uncertain City reappears.
- Verbal Tic: Bob Wire's lackeys, the Frags, have two. They tend to let out a series of gurgle-like noises at random, usually when they're goofing off or have nothing to say. And whenever one of them are talking, they'll randomly deepen their typically high-pitched voices, usually for emphasis, comedic timing, or as a sign that they mean business.
- Vernon tends to exclaim "Bwah!" quite a bit, even occasionally interjecting it into certain words.
- Viral Transformation: Monsteritis in its titular episode. It's contracted by being bit by a creature called a Frobish. It slowly turns its host into a monster over the course of a day. The only cure is eating the mouth slime of the Dongo Worm, which resides in the Uncertain City. Cliff gets it in "Monsteritis", spurring Russell to make the trip of the episode. Loopy is revealed to have got it from the Frobish as well, and has to be fed a spoonful of the slime to return to normal.
- Vocal Evolution: Mark Rendall, who voiced Russell, naturally goes through this as the series progresses, due to being a child actor at the time. As a result, his voice notably gets deeper from season to season.
- You Gotta Have Blue Hair: Auntie First has pink hair, and Ex-Princess Populah's is more a shade of purple.