- "The Kremling gang will take over the World with this thing!"
- ― King K. Rool in DK: Jungle Climber
King K. Rool is the main antagonist of the Donkey Kong franchise. He is a large Kremling crocodile with a gold crown, he rules over the Kremling Krew and tries to take over Donkey Kong Island. King K. Rool attempted to steal Kong Family members along with Donkey Kong's Banana Hoard. He went by the alias of Kaptain K. Rool being pirate themed in Donkey Kong Country 2: Diddy's Kong Quest and Donkey Kong Land 2 while in Donkey Kong Country 3: Dixie Kong's Double Trouble! and Donkey Kong Land III he went by the alias of Baron K. Roolenstein, which is mad scientist themed.
King K. Rool is an extremely obese Kremling who, in older games, encases his belly in golden armor. However, in more recent games such as Mario Super Sluggers, K. Rool's belly has no gold on it and simply has a fleshy texture. His face consists of having a large, crocodile-like snout with 8 top-teeth, each one being bigger the closer they are to his nose. his 4 bottom teeth are smaller than any of his top teeth and remain the same size. His two eyes are different from each other, as his right eye is simply a cartoony-looking oval shaped eye with a dotted pupil. His left eye though is much larger and is bloodshot, giving it a much more red appearance. On top of his head, King K. Rool wears a golden crown with circular figures on the tips. His crown was much larger in the older games with much more tips, but in recent games, his crown is smaller with less tippings. He also wear's a large, red cape with a yellow pattern on it. Strangely, in Super Smash Bros. Ultimate, his cape is torn. Is cape is attatched to him by a greenish-blue hexagonal gem. His wrists have golden bands on them.
King K. Rool's most common form, the King form which is used on all of the games he appears in except for Donkey Kong Country 2: Diddy's Kong Quest, Donkey Kong Country 3: Dixie Kong's Double Trouble, Donkey Kong Land 2, Donkey Kong Land III where he takes on the forms, Kaptain and Mad Scientist. He has a red cape and a sharp crown in his King form.
King K. Rool's second form is as a pirate where he is referred to Kaptain K. Rool. Him, along with many of his minions, are dressed up like pirates. He appears as this form in Donkey Kong Country 2: Diddy's Kong Quest and Donkey Kong Land 2. In this form, King K. Rool has a brown cloak on, a black pirate hat, a cannon shooting cannonballs, and a belt with a skull in it. Kaptain K. Rool uses the cannon as a weapon in the game. His name is derived from the word captain which is replaced by a K, explaining that K. Rool is a Kremling.
King K. Rool's third form is a mad scientist and he is referred to Baron K. Roolenstein. He has black wig, a jetpack with helicopter blades, and a white lab coat. He also has black gloves on. He mainly uses his jetpack as a weapon. King K. Rool takes on this form in Donkey Kong Country 3: Dixie Kong's Double Trouble! and Donkey Kong Land III. This name comes from a famous monster, Frankenstein.
King K. Rool's most recent form is a boxer, naming himself King Krusha K. Rool, and acts as the final boss of Donkey Kong 64. However, this is the only instance where King K. Rool is introduced as himself in the beginning of the game, only to change into this form during the final boss.
- His name may be an alternate form of the word “cruel.”
- K. Rool's persona, Kaptain K. Rool, is referenced in only one other game beside Donkey Kong Country 2: Diddy Kong's Quest, albeit obscurely; in Donkey Kong 64, inside the sunken ship off to a corner, there is a book entitled "Kaptain K. Rool's Log Book".
- Cranky Kong mentions in the Donkey Kong 64 instruction booklet that K. Rool had given up his silly disguises. While he has not seriously gone incognito since Baron K. Roolenstien, for the final fight he went by the moniker "King Krushaaaa K.Rool" as a boxer.
- Strangely enough, King K. Rool was originally depicted with a tail. The last time he physically had it was in Donkey Kong 64 - inexplicably, it is completely missing in subsequent appearances. This may have something to do with the implied brutal injuries he suffered at the end of the game.
- His tail is referred to in DK Jungle Climber where he says "But you lose for being a pain in my tail."
- According to Gregg Mayles (designer of Donkey Kong Country and the Banjo-Kazooie series) on Rareware.com's former "scribes" column, K. Rool's motivation for stealing the banana hoard is either that he wants Donkey Kong to starve to death so that he can occupy his treehouse or simply just the fact that he likes bananas. The latter explanation is contradicted in DK: Jungle Climber though, as K. Rool states he despises bananas.
- King K. Rool was also featured as the main villain of Nintendo's 2003 version of Camp Hyrule. King K. Rool caused chaos in Camp Hyrule by creating a massive earthquake.
- Interestingly, King K. Rool's name is pronounced two different ways during the first episode of the Donkey Kong Country television series. First, he was referred to as "King Kay-Rool" and then "King Kuh-Rool" shortly afterwards. However, after that episode, the former pronunciation was never used again.
- Tiki Tong seems to have a few similarities with King K. Rool; they both have an eye that's different from the other, and they both have reasons for stealing Donkey Kong's banana hoard.
- In nearly all the games in the Donkey Kong Country series, King K. Rool has been the final boss. However, in Donkey Kong Country Returns, he makes absence whatsoever, thus making it the first game in the Donkey Kong Country series where he is not the final boss. This has surprisingly been the case in the three latest games.
- King K. Rool also resembles King Koopa from The Adventures of Super Mario Bros. 3.
- K. Rool's Baron K. Roolenstein persona is based on a combination of Frankenstein's Monster as portrayed by Boris Karloff in the Universal Horror movie Frankenstein and the character of Baron Victor von Frankenstein (played by Peter Cushing) from the Hammer Horror Frankenstein series. Additionally it may also be a play on Albert Einstein, who is a real life scientist.