Charybdis

Charybdis is a character exclusive to the Winx Club Comic Series. He makes his first and only appearance in Issue 104: The Mirror of the Sea initially as a sea monster who was cursed by an ancient witch alongside his beloved, Scylla.

Monster
As a monster, he is a giant blue sea serpent, with fins along his body. He has sharp teeth and, red glowing eyes.

Human
He wears sandals, and a green and white toga like outfit. As a human he has light tan skin, dark eyes, and short black curly hair.

Personality
He is shown to care deeply for his fiancée, Scylla. But he can be a bit clueless as he was unaware that Circe had feelings for him. As a monster he's more aggressive, and comes off as a far more dangerous monster.

Pre-Comics
Charybdis and his fiancée were set to marry but the jealous Circe turned them both into sea monsters. From then on, they roamed the oceans together becoming terrifying mythologies to humans.

Season 5
He appears in the seas in front of the fishermen which invokes terror and disbelief within them. His appearance prompts Phylla to alert the Winx. He then appears again, breaching through the ocean surface, his towering size surprises the Winx. He dives into the sea again but his large size causes a large vortex which made the Winx believe he was attacking them.

Tecna tries to contain him in her spell but he bites through it. Bloom is about to try her spell on him but his fiancée grabs her arm. His fiancée's appearance frightens Bloom and when Phylla shouts at her to release her, his fiancée immediately does so. Scylla checks up on him, to see if he is okay. Flora noticed that Scylla did release Bloom, making her believe she had no intentions of harming them. So, Musa uses her power over music and through her magical flute is able to learn about Scylla and himself. Musa tells her friends that they are lovers and was set to marry but the jealous witch Circe who was in love with Charybdis cursed them into the terrifying creatures today, all because Charybdis rejected her. Charybdis and Scylla had lived in exile in depths of the sea since then.

Musa also clarified that Charybdis had no intention of attacking the fishermen but due to his large size, he would create large vortexes, and that he and Scylla are not evil, their appearance just terrified the fishermen.

The Winx want to help them and Musa explains that they would truly appreciate it but the only way to do that is to use the Mirror of the Sea to turn them back to humans. This is located on a deserted island not too far from where they are now. Since the Winx agreed to help them, Charybdis and Scylla show them the way to the mirror. Whilst they wait for the girls to find the mirror, Circe had awaken and stepped out of the lighthouse she had slept in for centuries, looking for the ones who interrupted her slumber. Charybdis and Scylla call out Circe which distracted her long enough for Stella to cast her light spell onto the Mirror of the Sea which turns Charybdis and Scylla back to their human-selves and Circe into a small crab.

Overjoyed to finally be able to embrace Scylla again, he thanks the Winx for breaking the spell.

Trivia

 * Charybdis was inspired by Charybdis, from Greek Mythology, who was a daughter of the Sea God Poseidon and the Earth Goddess Gaia. As punishment for supporting her father in a war against him, the King of the Gods, Poseidon's brother and Charybdis's uncle, Zeus, chained her to the bottom of the ocean and cursed her so she would become a monster with an uncontrollable thirst, which caused her to create large whirlpools when she drank sea water to quench her thirst. Charybdis was believed to live under a small rock on one side of a channel opposite to another dangerous monster, Scylla. Charybdis and Scylla were both very dangerous for ships who passed to close to them, and the channel they were located in was so narrow that sailors would be caught by one of them when they tried to avoid the other.
 * The story of Charybdis's and Scylla's channel is the origin of the proverb "Between Scylla and Charybdis", which refers to a situation where one has to choose the lesser between two evils or where one gets caught in a dangerous situation while trying to avoid a similarly dangerous situation.
 * According to the Greek mythological poem, The Odyssey, after leaving the island of the sorceress Circe, the hero Odysseus had to pass through the channel of Scylla and Charybdis and he chose to avoid Charybdis and pass near Scylla since Scylla was less dangerous.