Plutonium Mario 64 is a major ROM Hack made by usernamesarespiders, featuring 12 main courses with 101 Stars.

Originally dubbed Pluto Mario 64, this was an old Super Mario World hack the creator made years in the past but never was released in public until it was remade for Super Mario 64. It was named after the dwarf planet orbiting from the Sun, before deciding to name it after the chemical element, plutonium.

This hack is the second game which takes place in a uncommon land after Indigo Island, and similar to the Yoshi's Adventure series and Cup series, almost all the courses are accessible from the main overworld.

Aesthetic differences include different icons for Stars and coins, and the X and digits to the right of these icons. Bob-ombs also have many different colorations, such as mint green and purple. Signs are white instead of brown, and ! boxes have had their appearance altered in both solid and transparent forms.