The gray fox (Urocyon cinereoargenteus) is a mammal of the order Carnivora ranging throughout most of the southern half of North America from southern Canada to the northern part of South America (Venezuela and Colombia). This species and the closely related Channel Island fox (Urocyon littoralis) are the only living members of the genus Urocyon, which is considered to be among the most primitive of the living canids. Though it was once the most common fox in the east, and still is found there, human advancement allowed the red fox to become more dominant. The Pacific States still have the gray fox as a dominant.

The gray fox appeared during the mid Pliocene epoch 3.6 million years ago (AEO) with the first fossil evidence found at the lower 111 Ranch site, Graham County, Arizona with contemporary mammals giant sloth, the elephant-like Cuvieronius, Large-headed llama, and the early small horses of Nannippus and Equus. Genetic analyses of the fox-like canids confirmed that the gray fox is a distinct genus from the red foxes (Vulpes ssp.). Genetically, the gray fox often clusters with two other ancient lineages, the east Asian Raccoon dog (Nyctereutes procyonoides) and the African Bat-eared fox (Otocyon megalotis). Chromosome number is 2n=66. Recent genetic analysis has shown that the gray fox migrated into the northeastern United States post-Pleistocene in association with the Medieval Climate Anomaly warming trend. The Channel Island fox is likely descended from mainland gray foxes.

Solid Snake (ソリッド・スネーク, Soriddo Sunēku^?), real name David (デイビッド, Deibiddo^?), is a fictional character and the protagonist of Konami's Metal Gear series. Created by Hideo Kojima, Snake is introduced in the first game of the series, Metal Gear from 1987. Snake has appeared in the majority of subsequent games and spin-offs. Japanese voice actor Akio Ōtsuka voices Snake in Japanese, while actor and screenwriter David Hayter provides the English voice of the character.

Introduced in Metal Gear, Solid Snake is a combination of spy, special operations soldier, and mercenary commando of FOXHOUND – a black operations and espionage unit. He is tasked with disarming and destroying the latest incarnation of Metal Gear, a bipedal nuclear weapon-armed mecha. Controlled by the player, Solid Snake must act alone, supported via radio by commanding officers and specialists. While during his first two appearances Snake's designs were references to Hollywood films, by Metal Gear Solid he was given a consistent design by artist Yoji Shinkawa alongside an established personality.

Gray Fox (グレイ・フォックス, Gurei Fokkusu^?, spelled "Grey Fox" in the MSX2 games) is a fictional video game character in the Metal Gear series.

According to Hideo Kojima, "cyborg ninja was born from this Shin-chan's graffiti."

Gray Fox first appears in the original Metal Gear as a high-ranking agent of FOXHOUND (the "Fox" codename being the highest commemoration within the unit) who goes missing during a mission prior to the events of the game, his last transmission being a cryptic message simply saying "Metal Gear".Solid Snake's initial objective in the game is to rescue Gray Fox, who reveals the true nature of Metal Gear to the player.

Fox returns in Metal Gear 2, having left FOXHOUND and defected to Zanzibar Land to join Big Boss' side. Fox pilots the new model Metal Gear D and confronts Snake a few times, while secretly assisting him as an anonymous informant. Snake destroys Metal Gear D and ends up being challenged by Fox to a fistfight in the middle of a minefield. Fox's past is fleshed out in this game and his civilian identity is revealed to be Frank Jaeger (フランク・イェーガー, Furanku Yēgā^?, "Frank Yeager" in the MSX2 version), Naomi Hunter being his foster sister. His face portrait in the MSX2 version was modeled after actor Tom Berenger.