Donkey Kong (or D.K. for short or full name Donkey Kong the 3rd) is a gorilla that wears a red tie with his short name (D.K.). He fought Jumpman in 1981 in the first commercially successful video game called Donkey Kong, although later, he was stated to be Cranky Kong.
The current Donkey Kong is Cranky's grandson, the third generation in the Donkey Kong Lineage after his father Donkey Kong Jr., and first appeared in Donkey Kong Country as the main protagonist, along with his nephew/best friend Diddy Kong. He appeared in some of SuperMarioGlitchy4's bloopers.
Unlike in the first arcade games, where Mario fought with Cranky Kong (aka Donkey Kong Senior), the present day Donkey Kong is on friendlier terms with Mario in the spin-off games, despite a brief rivalry between the two in Mario vs Donkey Kong and its sequels. It is seemingly, more of a friendly rivalry, between Mario and Donkey Kong.
There is some debate as to whether or not the original Donkey Kong from the arcade games is Cranky Kong, and if Donkey Kong Junior. is the father of the modern Donkey Kong we all know and love. If this is the case, then that would create a huge time paradox in Mario Tennis, where the current Donkey Kong and a younger version of Donkey Kong Jr. are both playable together.
In the beta of Donkey Kong 64, DK had a shotgun, but in The Wacky Wario Bros.: Wario's Treasure Hunting Time, he had a real gun, as well.
Donkey Kong shoots anyone who steals his treasure as seen in The Wacky Wario Bros.: Wario's Treasure Hunting Time.
He hates Wario because he stole his treasure once.
He is sometimes referred to as "The Dong," or "Master Dong" by Jeeves and pretty much everyone else. SMG4 and Kevin even call him this on their gaming channel. It is meant to be a satirical combination of his first and last name.
In Welcome To The Kushroom Mingdom when SMG3 is saying who each of his kingdom's inhabitants are in relation to the inhabitants of the Mushroom Kingdom, he gets to DK's replacement and says "Konkey Dong" instead of "Donkey Kong." This was probably intentional, due to the running joke of shipping his first and last name to create "the Dong."