Other than Princess Stella, the following characters are from the planet Solaria.
King Radius: Stella's and Takaia's father. He almost marries Countess Cassandra. With the help of Valtor, Countess Cassandra controls King Radius to do whatever she says. Cassandra leaves King Radius in danger of getting killed by dragons in the 8th episode of season 3. However, Stella saves him and earns her Enchantix powers.
Ex-Queen Luna: Stella's mother. She and King Radius are divorced, but they later got back together in the later episodes in Season 5.
Countess Cassandra & Chimera: Mother and daughter duo introduced in season 3. Chimera appears in the 1st episode, constantly in conflict with the Winx as they shop in preparation for Stella's princess ball on Solaria. Countess Cassandra appears in the second episode, when the Winx girls arrive on Solaria. Both of them team up with Valtor to gain control of Solaria. Cassandra and Stella's and Takaia's father, King Radius, are engaged to be married. Cassandra puts a spell on Radius that forces him to do everything she tells him to, even banishing his own daughter. Chimera uses her powers to turn Stella into a hideous monster. Later in the season, Chimera takes Stella's place as 1st Princess of Solaria.