Star

Stars (or Soul Cakes during Halloween and Sugar Plums during Christmas) are common power-ups which can be dropped by any enemy with a chance of, as long as the player is below maximum mana. They are not inventory items, but are instead instantly consumed and restore 100 mana. Enemies will only drop Stars if the closest player is not at maximum mana.

It is also possible to spawn Stars (and their seasonal counterparts) with a Star Statue.

They can be collected within range of 2 blocks, which can be increased with Celestial Magnet and its upgrades.

Trivia

 * Soul Cakes are likely a reference to the real-life s, small round cakes which are traditionally made for, and  to commemorate the dead in the Christian tradition. They are often simply referred to as souls, and were given out to children and the poor (known as soulers), who would go from door to door during the days of  singing and saying prayers "for the souls of the givers and their friends". Each cake eaten would represent a soul being freed from purgatory. The custom was popular in England and Wales and has counterparts in other parts of the world that are practiced to this day. It is often seen as the origin for modern ing.
 * Although Stars are instantly consumed on pickup, it is possible to hack in Stars into the player's inventory through the use of editors. The hacked-in Stars still act like normal Stars, and will still be consumed on pickup, after dropping them in front of the player.
 * Mana Stars existed before Mana even existed. In the beta version of Terraria, Mana Stars would attempt to restore mana, but they did not do anything.
 * In worlds, all Stars have a  chance to be replaced by Soul Cakes and a  chance to be replaced by Sugar Plums, regardless of season.