Callisto

Callisto is a planet introduced in Season 1.

Overview
Callisto is the homeworld of Varanda, its princess. The planet is described as the "fourth world of Magix Realm's upper ring".

According to Obscurum, the planet has a star that is perfectly dry.

Season 1
In "Welcome to Magix!," according to Stella, Varanda of Callisto enrolled at Alfea but just before the start of the school year she entrusted her with a letter of withdrawal to be delivered to Faragonda. Stella, however, tore the letter, and Bloom pretended to be Varanda due to the fact that Bloom had not yet enrolled. Later that night, Stella unintentionally reveals Bloom's true identity to the Winx and Bloom confesses to Griselda and Faragonda.

Season 8
In "Into the Depths of Andros," Obscurum suggests to Valtor if he will conquer Callisto's star first since its planet is perfectly dry but Valtor gets annoyed before Obscurum could finish talking.

Season 1
In "The Castle," according to Stella, Varanda of Callisto enrolled at Alfea but just before the start of the school year she entrusted her with a letter of withdrawal to be delivered to Faragonda. Stella, however, tore the letter, and Bloom pretended to be Varanda due to the fact that Bloom had not yet enrolled. Later that night, Stella unintentionally reveals Bloom's true identity to the Winx and Bloom confesses to Griselda and Faragonda.

Trivia

 * Callisto's name might be derived from:
 * Callisto, a Moon of the planet Jupiter.
 * Callisto, the nymph from Greek Mythology based on whom the Moon of Jupiter was named.
 * In the 4Kids dub:
 * It is named "Vallisto".
 * It is renowned for its rich artistic traditions and its beaches are very popular with tourists.