the Rabbit from Super Mario 64
MIPS is a yellow rabbit found in the Castle Basement. He appears when Mario exits a course after collecting 15 stars or 50 stars. MIPS will run away if Mario tries to go near him, but if Mario manages to grab him MIPS will give Mario a star. 2 stars can be obtained from MIPS. MIPS was used extensively in early Nintendo 64 test simulations. Mario was originally going to be able to throw MIPS, but this was removed.
In speedrunning (16 Star), the trick called MIPS Clip is used to bypass the 30 Star Door that leads to Dire, Dire Docks and Bowser in the Fire Sea