Bigfoot is one of the more famous myths in GTA SA, He supposedly can be found in the San Andreas countryside (usually in Back o' Beyond or Mount Chiliad.

The majority of video or photo evidence that supposedly show Bigfoot's existence are either faked or are a mod. The debate that determines if Bigfoot exists in San Andreas is still active to this day.

The existence of Bigfoot in GTA SA has been the focal point of many internet-based rumors since the game was released in 2004. It is impossible to determine the start of these rumours. However, one theory suggests that the rumours may have been started by the integration of the artist Bigfoot in the brochure that came with the game.

There are many supposed in-game references including evidence that supports that Bigfoot can be found in-game. One is a picture by the TV in the Johnson house that depicts what looks like Bigfoot surrounded by the Back o' Beyond scenery. Another is that the entire section of Back o' Beyond on the in-game map looks like a footprint The whole idea of Bigfoot's existence fits nicely into the diverse world of the San Andreas countryside, especially its Flint County and Whetstone areas, with large virgin forests and "spooky" locations. The most popular reported sighting locations are near the cave on the side of Mount Chiliad, the Shady Cabin area, and Shady creek cabin. Several screenshots and videos have been posted claiming to show the creature in the game. Sometimes genuine in-game captures of unofficial modifications or edited (photoshopped) images and videos can fool players. While Bigfoot can be found only in the early version of the game or the PS2 console. But the newer versions of it and are removed only with the aid of modification.

In an official interview with Terry Donovan released in 2005, he stated, "There is no Bigfoot, just like in real life. But there is something in the woods." However, there is a small but vocal group of supporters of the creature's existence. Many people take Donovan's message as a hint, and search for Piggsy and other similar creatures in the San Andreas countryside. But a few months later, Sam Houser stated "I did in fact put Bigfoot in the game which was meant as a joke but my boss told me to remove it. Instead, I didn't tell my boss and kept Bigfoot in the game just in case testers decided to roam the woods. Players will have a 1/10 chance of finding Bigfoot.