Omnia

Omnia is the Queen guardian of Sirenix.

Season 5
In "Sirenix," the Winx restored the source of lake of Roccaluce after Tritannus stole it's power. The Sirenix guardians open the gate to the Infinite Ocean the, Omnia invited the Winx to enter the Sirenix gate.

Omnia tells the Winx that the infinite ocean is always open to them, then, she told the fairies that Tritannus and The Trix were in the infinite ocean too.

Appearance
Omnia is a yellow skinned mini-mermaid with a long and adorned tail, she and the Sirenix guardians looks like the undines that appeared in the first season.

She has a pink shell-shaped tiara, some orange bracelets, yellow hair, and a pink shell on her chest.

Trivia

 * She is a much larger version of the Sirenix Guardians.
 * She looks a bit like Stella's Sirenix Guardian.