A Ztar has an opposite effect of a Star. Instead of granting a Star to the player,it removes one from the player.
Ztars make their first appearance in Mario Party, they are the Bowser Bogus item in Mario's Rainbow Castle. They do not count as a negative to the player's Star count in this game.
If the player lands on a Bowser Space and got the event titled "Bowser's Multiplying Toads", Bowser will create two Toads, one of which is real and the other is a Koopa Kid in disguise. If the player runs into one of the "Toad"s it will offer a "Star" for the price of twenty coins, it is revealed to be either a Star or a Ztar once paind. If the Ztar appears, it will not count towards the player's amount of Stars and twenty coins are wasted. The other Toad will still offer a real Star.
In Thwomp's Backroom Ball, a Ztar is seen hosting the game of volleyball.
If a player lands on a Bowser Space and has at least one Star, Bowser will occasionally give a Ztar to the player, which will subtract a Star from the current total of the player. It is impossible to go below zero Stars. However, in Card Party, a player can go below zero if a Ztar Star card is revealed. Additionally, in the Super Battle mode, the Ztar is the optional Engine type for the power source.
Renamed to Shadow Stars, Bowser gives a player a Shadow Star in Clockwork Castle if the player has one or more Stars. If the player has no Stars, Bowser gives them a Special Shadow Star which will take away Coins instead. Bowser gives the player a Shadow Star if they land on Bowser's Battle Yacht in Castaway Bay.
Renamed to Dark Stars, a place must choose a chest in Grand Canal, one of which contains a Dark Star, if the player chooses this chest, they must take the Ztar. During Bowser Time in Neon Heights, Bowser will occasionally put a Dark Star in one of the chests, if the player pays a Koopa Kid for the chest, they are required to take the Dark Star.
Back to the original name of Ztar, they occasionally appear in Hidden Blocks. If a player gets one, they will lose a Star.
In Mario Party 9 & 10, Mini Ztars appear as a regular element and count against a player's Mini Stars total if collected. In Mario Party: Island Tour, they only appear on the board, Star-Crossed Skyway and have the same function as before.
- The Ztar's jingle is a reversed version of the Star's jingle.