There is a recurring character within the Metal Gear Solid series called "Johnny". In each game, Snake will come across a character named Johnny, never being the same person but rather a member of a long line of Johnnys from the same family. In each instance, Johnny can suffer from severe diarrhea.

In the first Metal Gear Solid, Johnny is encountered twice. First he is found passed out and naked by the cells in which Maryl escapes, and later he guards Snake's cell before he is tortured.

In Metal Gear Solid 3, Johnny reveals a lot of back story to Snake while guarding his cell, giving insight into his family's tradition of naming every male born into the family "Johnny".

In Metal Gear Solid 4, Johnny is found suffering from diarrhea in a metal barrel, and is constantly suffering from bowel trouble throughout the story. This time, Johnny plays a protagonist, and a major role in the game's story as well.