In the Dungeons & Dragons fantasy role-playing game, the foo creature is a type of outsider creature.
Foo creature Wikipedia
The foo dog and the foo lion first appeared in the first edition Monster Manual II (1983).
The foo dog and the foo lion appeared in second edition for the Kara-Tur setting in the Monstrous Compendium Kara-Tur Appendix (1990). The foo dog and the foo lion appeared for the Planescape setting in the first Planescape Monstrous Compendium Appendix (1994), and the Guide to the Ethereal Plane (1998).
A foo creature is found on the Upper Outer Planes, and can sometimes be convinced to serve and guard humans.
The foo creature appeared as a template in the Tome of Horrors (2002) from Necromancer Games.
The foo creature (including the foo dog and foo lion) appeared in Paizo Publishing's book Pathfinder Roleplaying Game Bestiary 3 (2011), on pages 120-121.