The 121st Star

The 121st Star is an anomalous Power Star that can be found in many personalized copies. It was one of the most popular rumors when Super Mario 64 was released, as people believed there might be more beyond the 120 standard stars in the game. The way to get the 121st Star is very inconsistent, likely as a result of playground rumors being blended with true personalized experiences, though some methods are more common than others, likely the actual ones that were found by players.

List of Methods
''Below is a list of some of the many ways to supposedly unlock the 121st Star. Note that some of these may be fabricated due to the widespread nature of this rumor or could be found simultaneously to add up to 122 or more.''


 * Finding an extra Mission not found in standard copies, such as a 16th 100 Coin Star.
 * Grabbing any star from unused courses/sub areas or other Anomalous Areas implemented by the A.I.
 * Obtaining it from Yoshi upon speaking to him, along with the other gifts obtained from them. This does not happen in standard copies.
 * Reaching a Minor Anomalous Location, occassionally through Backward Long Jumping.
 * Finding an anomalous Star-granting NPC, such as another MIPS or a 4th star-giving Toad.
 * Using the Vanish Cap to get behind the mirror in the Second Floor. Notably, this method is a hidden star in Super Mario 64 DS.
 * Obtaining the star at the end of Bowser in the Sky. Notably, this does not increment the star counter in standard copies.
 * Obtaining the Eternal Star, Book on Bad, Discolored Star or another anomalous collectible.

The Star's Effects
Due to the nature of owning that many Power Stars, there are many reported effects and unlockables associated with collecting the 121st Power Star. Like above, some of these may be fabricated rumours, so the more common reports have been collected. Take all information with a grain of salt.


 * Unlocking the Fourth Floor or another anomalous area of Princess Peach's Castle.
 * Unlocking an Unintended Playable Character.
 * Special dialogue when defeating Bowser, usually resulting in an Alternate Ending.
 * Gaining access to a new Course or Minor Anomalous Location.

These effects may also result in even more anomalous Power Stars, resulting in star counts far surpassing the standard 120. Reports of more than 150~ total Power Stars are rare, and numbers exceedingly high are considered unlikely or impossible due to the limited space of the Nintendo 64.

Trivia

 * A similar rumor exists for the DS version about a "151st" star.