Gunter

"Of all history's greatest monsters, you are by far the most evil thing i've ever encountered"-Marceline's Father

Gunter (or Gunther) is Ice King's main penguin servant and his only friend. Gunter's gender is unknown and purposefully left ambiguous. (See the "Gender and identity" section.)

In "What is Life?," one of Gunter's known duties is being used as a stand for the Ice King's video game machine. Gunter also tried to warn the Ice King that Finn and Neptr were in the room. Gunter may be one of the penguins seen in the Theme Song, in the Ice Kingdom. Gunter may also have appeared in other episodes featuring penguins, although it's impossible to tell because Gunter is indistinguishable from other penguins. Gunter is mentioned in "What Have You Done?" when Ice King says: "Gunter, pick up Finn's dead carcass." Gunter appears again in "It Came from the Nightosphere," where he/she' soul is almost stolen and is dubbed "the most evil thing (in the world)" by Marceline's Dad. Gunter appears in "The Chamber of Frozen Blades" and is very sick, but it later turns out he/she was pregnant, and the egg hatches, revealing a floating pink kitten.

Gunter re-appears in the episode "Still", trying to mess with the potions Ice King brought to freeze Finn and Jake.

Appearance
Gunter looks like a regular penguin with big black eyes, a navy blue back, and a white flat belly. Gunter is apparently very fat for a penguin, as Ice King has called her, "Daddy's little fatty", though this may only be a joke or a show of affection on Ice King's part. The latter is likely, since Gunter looks exactly like every other penguin in the Ice Kingdom. Although Gunter is a penguin, he/she makes a "quacking" sound. Gunter also likes to break bottles of many kinds, such as the two bottles in the episode "still".

Relationships
The Ice King sometimes gets agitated by Gunter's actions, such as when he/she accidentally broke his video game, but the Ice King seems to appreciate her company. Gunter is very loyal to the Ice King and even though he/she is his servant, Gunter occasionally wanders off. Gunter may be Ice King's best friend, but may also be his only friend. Ice King seems to pay more attention to Gunter then the rest of his penguin servents.

Gender and identity
The gender of Gunter is unknown and was left purposefully ambiguous.
 * In the episode "The Chamber of Frozen Blades", Gunter lays an egg. In the real world, only female birds lay eggs. However, since the egg contained a kitten, it's possible that real world rules do not apply or that Gunter is mutated or that it is some magical explanation.One more possibility is that he might be holding the egg like a regulular male penguin in the winter.
 * Ice King believed that Gunter is male. However, when questioned about it, he seemed to not really be sure and simply shrugged off the question.
 * "Gunter" is generally a male first name. This name though was probably given by the Ice King who, as recently stated, isn't truely sure what Gunter is. He more than likely just guessed, which is of course not enough ground to be sure whether Gunter is male or female.
 * Series writer Adam Muto provided a cryptic answer about Gunter's gender, saying "There's an even deeper question you're missing. One that I hope we'll address in a future episode."
 * Series character designer Natasha Allegri suggested that "Gunter" might always be a different penguin, and that it's just the name Ice King calls "whatever penguin hangs around him the longest."
 * In the episode "Still", Ice King possibly infers there may be more than one Gunter or that it is whatever penguin is around him at that time, considering that he refers to the one with him as "this one", inferring that it isn't the only Gunter. However, "this one" may be a term of endearment.

Trivia

 * Gunter, for some reason, was dubbed the most evil creature that Marceline's Dad had ever seen, indicating Gunter may secretly be evil and smarter than others realize.
 * The father of the pink kitten that comes out of the egg Gunter nurtures is unknown.
 * In "What is Life?" the Ice King comments on Gunter gaining weight. This may foreshadow Gunter's pregnancy.
 * Finn and Jake must have known Gunter because they were surprised when they found out that Gunter was a woman (or at least assumed female because Gunter laid the egg).
 * The name is spelled Gunter, but pronounced in several different ways, according to Adam Muto.
 * Gunter has a strange facination with breaking bottles, according to the Ice King in "Still".