Ice King's castle
The only known fortification (other than the Snow Golem's cabin from the episode "Thank You") in the kingdom is the Ice King's castle. The castle is basically a hollow mountain capped by snow and ice, with the main entrance being a face-like set of windows near the top. Ice King's main living room contains a fancy bed, a drum kit, and weightlifting equipment. The room usually has underpants and old pizza boxes strewn across the floor. There is also a cage where Ice King keeps his kidnapped princesses. There are several secret rooms, including what appears to be a basement filled with monsters and technology seen in "What is Life?" and a secret chamber full of ninja collectibles seen in "The Chamber of Frozen Blades." In the episode "Princess Monster Wife," it is shown there is a large network of tunnels and open spaces in the castle, one having herds of Ice Bulls, as well as a kitchen and dining room. In the episode "Beyond this Earthly Realm," it is shown Ice King has a room in his basement with a portal to the Spirit World, which is actually the Mystery Cave. This room seems to have fog billowing on the floors. In "I Remember You," Ice King has a "The Past" room, where he keeps memorabilia of himself and some objects that he had when he was still Simon Petrikov. It is revealed in "Frost & Fire" that the Ice Castle can be controlled like a giant robot. This castle, along with presumably everything in it, is destroyed by Flame Princess. Ice King then moves in with Finn and Jake and leaves the reconstruction of his kingdom to Gunter and the other penguins. In "Play Date", Ice King finally moves back into the castle.
Ice Kingdom Law
It is noted in "Prisoners of Love" that there is an Ice Kingdom law with at least one rule: no trespassing. The Ice King accuses Finn and Jake of breaking this law on multiple occasions. However, in the very later episodes, Ice King seems to allow anyone to enter the Ice Kingdom. (For example, Ice King saw Finn and Flame Princess having a picnic in the Ice Kingdom in the episode "Frost & Fire.") This must be because of the changing of his personality in the later episodes. In "When Wedding Bells Thaw," Ice King implies that a traditional wedding in the Ice Kingdom apparently involves tying up the bride, lowering her on a rope, and touching her to the groom's beard. The ropes allegedly bring good luck to the marriage, although this may have been a lie to help him abduct princesses. In "Another Five More Short Graybles," it is shown that Ice King gave his penguins the right to vote. Thus it could be said that the Ice Kingdom is a democratic monarchy.
- Ice King
- Ice Queen (fictional)
- Simon Petrikov (previously, in "Betty" before becoming Ice King again)
- Snow Golems
- Patience St. Pim (as of "Elemental")
- Fionna and Cake Omnibus
- Ice Bull
- Ice Toads
- Walrus 1
- Walrus 5
- The Ice Kingdom is often seen in the background of scenes that take place near Finn and Jake's Tree Fort and the Candy Kingdom.
- The Ice King's basement in "What is Life?," besides being filled with technology and ice constructs, has a long stairway with carvings of faces similar to the entrance's face-like window opening.
- In the online game Jumping Finn, for some reason, the kingdom is called the Frozen Land.
- In "Holly Jolly Secrets Part I," Ice King inadvertently describes the Ice Kingdom when asked about the weather in the Candy Kingdom while pretending to be Princess Bubblegum over the phone, saying, "Oh, the usual. There's ice everywhere and it smells like penguins."
- In "Evicted!," the Ice Kingdom is near a lake/ocean, probably Iceberg Lake. In "Five Short Graybles," Ice King sends Gunter away on an iceberg, and in "Princess Monster Wife," a picture in the Ice King's room shows the kingdom above a body of water. In "The Party's Over, Isla de Señorita," the Ice King is seen rowing away in an ocean.
- It is possible that the Ice Kingdom is where Simon Petrikov (Ice King) used to live before he lost his sanity. In "Holly Jolly Secrets Part II," in the videos that showed Simon, snow burying the buildings can be seen, which probably formed the Ice Kingdom over time.
- Spirits can also be seen in the Ice Kingdom as shown in "Beyond this Earthly Realm."
- In "Finn the Human," it is revealed that if the crown loses its master, it reacts by covering the world in ice. Therefore, the Ice Kingdom may be a result of an unsuccessful attempt to separate Simon from the crown.
- In "Betty," after Ice King loses his powers the Ice Kingdom can be seen melting implying that the kingdom is actively kept frozen by the Ice King's power and melts, or reverts to normal weather patterns when no longer influenced by him.
- As seen in the promo Ice King ID Ice Kingdom appears to be near Malasia.