Justin Bailey

Samus Aran has put on a generic bikini swimsuit for several of her appearances. The first appearance of a bikini was in Metroid. Samus wears a bikini only if the game is completed in the very shortest amount of time. (These time limits have varied from under one hour to under two hours to under three hours, depending on the game.) In the original Metroid, each ending sequence but two (the "worst" of them) was notable for revealing that Samus, underneath her Power Suit, is actually a woman. (Not only was her gender hidden by the suit, but in both the American manual and press releases Samus was referred to as male. This was not an issue in Japan, where Samus was described with gender-neutral pronouns.) However, for several games after, the bikini continued to appear as traditional fastest-completion ending sequence attire, even though it is well-established that Samus is female. The persistent appearances of the skimpy bikini are likely intended as ‘rewards’ for beating the games quickly as Samus is considered to be attractive (something that is stated in the manga). The bikini was later replaced by the less revealing Zero Suit.

The appearance of the bikini has varied throughout its appearances. Metroid featured a pink leotard that was the playable suit in Metroid as well as a two piece pink bikini. Metroid II: Return of Samus featured a tank top and underwear, which would be colored red if a Super Game Boy, Game Boy Player or Game Boy Advance was used. Super Metroid featured a black sport bra and underwear, with matching boots. Metroid Fusion also featured the same type of bra as Super Metroid, but colored blue and featuring shorts. Despite the introduction of the Zero Suit, however, Zero Mission also featured a bikini in the vein of Super Metroid and Metroid Fusion, though colored orange.

The bikini is a usable suit in the original Metroid for NES (But not on Japan's Famicom Disk System), accessible by achieving the best ending, using the famous "JUSTIN BAILEY" password and variants or pressing start at the end of the credits (regardless of the ending). The bikini also appears in the game over for Super Metroid and Metroid Fusion.

Zero Suit Samus' palette swaps in Super Smash Bros. Brawl may be references to her bikinis in Fusion, Metroid and Super Metroid.

Trivia

 * The Metroid e-Manga depicts Samus in a light pink jumpsuit with brown hair; possibly as a nod to the bikini in Metroid.