Power Star

Power Stars, also known as Stars, are the main collectible of Super Mario 64. Bowser uses their power for various things such as making worlds within the paintings and sealing doors to stop Mario. A course has six Stars and a hundred coin Star, while a level has one or two, typically for collecting eight red coins, though in personalized copies levels may have up to around five while courses may on rare occasion have beyond seven. Additionally, several Stars will be hidden through the Castle or other hub worlds. There are usually 120 stars in total, but the total can surpass far beyond that. There can even be less than 120 stars.

Phenomena

Ztars

Ztars are the colloquial name for an anomalous form of Power Star due to their resemblance to the item from the Mario Party series. They have similar appearance and function as a “negative Star” though details vary. They appear as a dark gray or black, uncommonly with a blue or purple tint, and with light gray or pure white eyes, sometimes with a furrowed expression causing an angrier appearance. They are most commonly said to appear as a punishment for failing a Star mission, such as dropping a baby penguin off the edge of Cool, Cool Mountain or losing to Koopa the Quick. Upon collection, they are said to play a unique variant of the Star collection jingle and boot out of the level, typically as a simple exit for when a Star has been rendered uncollectable.

Many will say that Ztars can have more repercussions, such as one’s appearance rendering all Stars in the stage uncollectable, possibly even disabling the exit course option, forcing the player to either lose a life or collect the Ztar. The consequences of doing so are usually said to be causing the player to lose a life anyway or decreasing the player’s Star counter by one, similar to their role in Mario Party. Most report that they simply had to complete a random mission again, though some say the Star is permanently removed. According to some reports, a collected Ztar will appear on the mission select screen in place of the Star the player was attempting to collect, possibly as a mere cosmetic indicator that a Ztar was collected for that mission until the actual Star is collected, though some warn that the Ztar may make the mission unselectable and thereby remove a Star from the game, if it didn’t already.

Alternatively, some say Ztars may appear as a side collectible, either as random collectibles hidden normally or with courses having entire sets of Ztars to be collected. Either way, they would then be used to unlock special Ztar doors or complete similar objectives. Some have also claimed that collecting this type of Ztar may still remove a Star.

Star Discoloring

Star Discoloring, considered an equivalent anomaly to Coin Discoloring and Enemy Discoloring, and also generally associated with Dynamic Level Rearrangement, is a rarer anomaly that creates new types of Power Stars with new behaviors that typically scale from negative to positive and appear based on the player's skill at the game, with positive stars appearing more often to help people who aren't good at the game, and negative stars appearing to skilled players in order to add an extra challenge.

These are simply the most common behavior reported of these discolored stars and may be different from copy to copy. Some discolored stars are also unconfirmed, so it is wise to take them with a grain of salt. Finally, most of these stars have simply been reported to be recolors of regular Power Stars, though this page will only cover the manifestations of these stars that have unique mechanics.

Green	Green Stars are the most common instance of Star Discoloring and appear to have been reused in later Super Mario Bros. games by Nintendo, either by coincidence or due to them being inspired by this anomaly. Green Stars have been reported to appear in numbers of 1-3 in every main course, harder to find, and also considered "extra" collectibles. They would either contribute 2-3 stars to the overall star counter or have their own section of the game's HUD and unlock special levels, most commonly Challenge Courses.
Gray	Often confused with Silver Stars manifesting in the original Super Mario 64, Gray Stars function in a similar manner to red coins and secrets, though they have an inconsistent overall total in a level, ranging from 3-12 Gray Stars being required to obtain a standard Power Star, or potentially other discolored stars. Gray Stars are also stationary, unlike Silver Stars.
black	Often confused with Power Ztars which are entirely different objects distinguishable by appearance, black stars take away from the star counter instead of adding to it and are much more common in levels than regular Power Stars. Some players have reported that stars do not go translucent as they normally do upon being collected but are instead replaced by Black Stars. To compensate for the inconvenience this would otherwise cause, they are often found near their counterpart's former location, and the original star usually respawns without having to reload the level.
Cyan	Cyan Stars appear to be post-game stars found in every main course, and appear in groups of 1-3, similarly to Green Stars. Some reports state they can unlock new floors such as the 4th Floor, though most reports do not back this up and instead claim they are used to unlock the cannon in the Castle Grounds in order to talk to Yoshi or increase the Power Star account by 2-5. Coincidentally, ridable Yoshis have been reported to be more common in copies with Cyan Stars, especially when unlocked by talking to Yoshi on the rooftop.
red	Red Stars reportedly either increase the player's star count by 3-5 or increase the star counter by one. These stars are notable because they cause enemies and bosses to become more aggressive, gain more health and/or deal more damage, making the game much more difficult. They most often appear in Hard Mode, however may also appear outside of it if the A.I believes the player to be particularly experienced.
Rainbow	Rainbow Stars, similarly to the Rainbow Cap, usually function as a power-up similar to the aforementioned anomalous cap or replace the Metal Cap. Alternatively, they have been reported to increase the player's star count by 5-15. In both manifestations, they are the rarest instance of Star Discoloring, often requiring intentionally performing poorly to make them appear. They are by far the most challenging discolored star to collect, as well, as, for example, the first report of Rainbow Stars said that the player had to use the cannon to shoot out into the void to attempt to hit it, and that it disappeared forever after they failed to obtain it.
Purple	Purple Stars, also known as Dark Stars, are anomalous Power Stars seen in the unreleased Mario's Adventure game for the Special 64 that have been reported to appear in Super Mario 64. They usually appear in place of Power Stars obtained by defeating bosses, likely due to their connection to boss fights in Mario's Adventure. They usually only give 1 Power Star, though can give up to five Power Stars, with the difficulty of the boss fights scaling with the amount of Power Stars obtained by collecting a Dark Star.
Pink	Pink Stars are notable examples of discolored stars because they appear to change size as they spin, which usually causes erratic behavior. However, this often time "freezes", meaning many who encounter them will see them just as larger Power Stars and perhaps a glitch. No special changes or unlocks have been reported from Pink Stars, meaning they may have just been an object test for the A.I. to see if it could manipulate object size. Strangely enough, some have even reported the star seen after clearing Bowser in the Sky to become a Pink Star. What this means is unclear.