Power Star
In Super Mario 64 and Super Mario 64 DS games, Power Stars are spread throughout the worlds, and Mario (or in the Nintendo DS remake, Mario, Yoshi, Luigi, and Wario) is sent to go find them all. There are 7 power stars (8 in DS remake) to collect in each world, and after finding 70 of them (80 in DS remake), the final boss, Bowser, can be defeated. There are 150 Power Stars in all, as of Super Mario 64 DS, but only 120 were in the original.
Stars have since been a recurring theme in Mario, but in particular Power Stars are used often in the Mario Party series of games. As of late, however, they have been phased out in favor of Shine Sprites.
There are also Silver Stars which arent as powerful as Power Stars but 5 of them will get you one.
The Power Star was also a Gaddget in Mario Party Advance. Its description read, "Be the envy of all your friends with the dreamy power star!" The Power Star was the hardest Gaddget to earn, as it had to be bought for 100,000 coins.
