Great Greed is an environmentally-themed role-playing video game for the Nintendo Game Boy released by Namco in 1992.

The game's plot deals with a protagonist whose name that the player sets, but referred to as "Sierra Sam" in the game's promotional materials. Sam, a resident of the "real world," is transported to the fictional world of Greene in order to prevent Biohazard Harry (simply referred to as "Bio-Haz" in the game) from continuing to pollute Greene, a world of seven nations. Sam finds himself stuck in Greene because Microwave, who brought him there in the first place, lost her power in the previous battle. Sam's adventures range from collecting debut records to helping to expose a corrupt politician.

The game plays similarly to many other RPGs of the time, although there are a few significant differences. The graphics are very similar to those of Final Fantasy Legend and Final Fantasy Legend 2. However, battles are reminiscent of Dragon Warrior. Only one character fights (Sam), and only one monster fights at a time. The game features random encounter battles, and the player's progress can be saved anytime, except during battle, by using the select button. Additionally, most of the characters, enemies, and towns in the game are named after different types of food or food-related products.

Through the menu screen, the player can talk to the party for information on where to go next.