Culex is an optional hidden boss who appears in Super Mario RPG: Legend of the Seven Stars. Culex is a being from a different dimension who desires to do battle with warriors from Mario's world. He appears to be a type of demon, having dark purple skin, red twisted horns and wings, a red mark along his torso, a jagged tail, and several crystals surrounding his waist. He also emanates what appears to be dark energy.
Alongside the Crystals, Culex is an even more powerful boss than the main story's antagonist, Smithy, as he has 4,096 HP, the second most of any encounter in the game (behind only Smithy's second phase). Culex, combined with the Crystals, has 12,396 HP, which exceeds both of Smithy's phases combined.
Culex resides in a cross-dimensional region found behind a sealed door in Monstro Town. According to one of his neighbors, a Piranha Plant, Culex is "always mumbling about Crystal-this and an Evil-that." The sealed door that leads to Culex requires a Shiny Stone, also mentioned by the Piranha Plant. When Mario enters the region, Culex greets him and explains his story. He then challenges the party to a battle, which the player can either accept or refuse.
In battle, Culex is aided by four Crystals – the Earth Crystal, the Fire Crystal, the Water Crystal, and the Wind Crystal. These Crystals have magical attacks that correspond with their elemental power. All four Crystals can be defeated independently before targeting Culex, but if Culex falls, any remaining Crystals shatter one by one on their next turn.
If Mario's party wins, Culex rewards Mario with the Quartz Charm. Culex then leaves Mario's dimension as Mario is transported back to Monstro Town. The door to Culex also vanishes, leaving a solid rock wall in its place.
Culex's alignment and motives differ drastically between the Japanese and English versions. In the Japanese version, Culex claims to be a timeless overlord made of pure evil. As a two-dimensional being, he is perplexed by the three-dimensional forms of Mario's party, so he demands a fight to try and understand them. Upon defeat, he recognizes the party's strength and positive energy, and he and his pocket dimension disappear until the day he finally gains the solidity of the third dimension. In the English version, Culex's dialogue and backstory are completely rewritten: he is said to be a "Dark Knight of Vanda" sent by the Dark Mage, but his plans came to a halt after discovering that Mario's world is uninhabitable to him and his kind. He remains in a secured location in the hopes that the world's "strongest knight" will seek him for a challenge before he departs. He has nobler mannerisms, and attempts to leave Mario's company on good terms.
Allusions to Final Fantasy
Culex himself is an allusion to the Final Fantasy series, as Super Mario RPG: Legend of the Seven Stars is developed by Squaresoft, who are the creators of the Final Fantasy series. Culex has two different sets of game sprites, one for the overworld and a much larger one for battle, with the former being from a more top-down perspective instead of isometric like other enemies. His overworld sprite resembles enemy designs in the 2D Final Fantasy titles, and these sprites do not have as complex animations and frames, reminiscent of early Final Fantasy games. Moreover, the three music tracks associated with Culex are rearrangements of three music tracks from the Final Fantasy series: his battle music is a rearrangement of the boss battle theme from Final Fantasy IV, the music that plays when he is defeated is a rearrangement of the victory music present throughout the Final Fantasy series, and the ending conversation is an arrangement of the Final Fantasy "Prelude".
Names in other languages