Starfy

Starfy is the main character and the hero of The Legendary Starfy series, known as Densetsu no Stafy in Japan and originally released in this region only since 2002. The fifth game was released on June 8, 2009 in North America under the name The Legendary Starfy. Previously, he was referred to as by his Japanese name Stafy in English media.

The The Legendary Starfy series itself was created by TOSE, a second-party video game developing company of Nintendo. Starfy has made four cameos in Mario or Mario-related games; some Mario characters also appear in Starfy's games.

Mario & Luigi: Superstar Saga
In Mario & Luigi: Superstar Saga, Starfy made a cameo appearance on a movie poster in the Yoshi Theater.

Super Princess Peach
In Super Princess Peach, Starfy makes a cameo as the enemy known as "Starfish". The game's Glossary even describes him as "A star-shaped foe rumored to be the prince of a kingdom?"

Super Smash Bros. Brawl
Starfy also appears in Super Smash Bros. Brawl, as an Assist Trophy character. However, unlike most Assist Trophies, Starfy is vulnerable to opposing attacks, and can be sent flying out of the stage easily. He makes up for this with strong attacks, as well as a wide range of moves, such as a spin attack, and a fiery explosion.

Densetsu no Stafy 3
In Densetsu no Stafy 3, Wario makes a cameo appearance in World 8. Throughout this world, Wario assists Starfy with completing the levels, giving the player four different treasures - a "Wario cap", a Wario nose/mustache combo, a copy of WarioWare, Inc. with a Game Boy Advance, and a pile of gold. In each level, Wario is affected by one of his three more common status effects - Puffy Wario, Flaming Wario and Bubble Wario, all of which Wario uses to help Starfy complete the level.

Densetsu no Stafy 4
In Densetsu no Stafy 4, one of the collectable costumes for Starfy and his sister Starly (Stapy in Japan) is based on Princess Peach. Starly is also holding Perry, the parasol from Super Princess Peach. This costume is one of the winners of a costume designing contest held in Japan for fans.

Trivia

 * Contrary to popular belief, Starfy is neither a starfish nor a star.