The Trix are a trio of witches, and the main antagonists of the show. They consist of three witches who are also sisters and they descend from the Ancestral Witches, the most powerful and evil of all witches to have ever existed. They focus on what they are best at: acting maliciously and joining forces with the darkest villains the Magic Dimension has to offer.
The Trix call each other "sisters" and it is assumed that they are indeed really biological sisters, as there are no other known witch covens, except the Ancestral Witches, therefore acknowledging them as siblings. In "Twinning With The Witches", Griffin tells the Winx that Witches never work in groups as they always tend to betray each other, thus ruling out the possibility of Witch covens existing in the Winx Club universe. Despite this, they use a convergence in "The End of Tritannus". Considering the unusual solidarity among them, the fact that all three of them claim descent from the Ancestral Witches, and that they, along with the Ancestral Witches, are the only Witches known to have worked in groups, it is assumed that they are indeed biological sisters. This is confirmed in "The Problems of Love" when Stormy yells, "We're your sisters!" A setback is also made to this when Stella said, "Let's show these stepsisters a lesson." although that just might have been an insult.
- The name Trix originates the feminine form of the suffix "-tor" meaning doer and is the suffix for pracantatrix, incantrix, and praecantrix, all meaning "witch" in Latin. The name also originates from the Latin root word tri meaning three.
- Trix could be a pun on the word tricks.
- The Trix, Selina, and Kalshara are the only female villains aside from the movies.
- In the Harry Potter series, one of the Death-Eaters, most loyal to the Dark Lord Voldemort is named Bellatrix, meaning "she-warrior". She has a sadistic personality similar to that of the Trix and like them behaves in a cruel, demented and pitiless way, and she also wears clothes similar to those of the Trix in the Harry Potter film series. However unlike the Trix who work only for their own account, Bellatrix is completely devoted to Voldemort.
- However, in Season 3 they work for Valtor, who is similar to Voldemort, and display affection for him similar to Bellatrix's love for Voldemort, although unlike Bellatrix they later turn against him.
- Season 4 is the only one in which the Trix do not appear physically.
- In Magical Adventure, the Trix's appearances were altered. Icy's and Darcy's eye make-up only covered their eyes and not part of their cheeks. Only Stormy remains the same.
- In Season 3, the Winx Club's Enchantix allowed them to easily overpower the Trix. However, in Magical Adventure and Season 5, the Trix were more or less able to equal the Winx Club in battle, until their ancestors and Tritannus interfered.
- The Trix are back into their original witch forms in the second episode of the sixth season.
- In "The Legendarium", it never was shown how the Trix got more powerful than the Winx.
- According to Iginio Straffi, the Trix are triplets and were born on May 5.
- They came out in the Nickelodeon Winx Club game, Bloomix Battle along with all the Winx.
- Since the first moment they were seen in the series, the Trix are the villains that lasted the longest before they got defeated by the Winx Club once and for all.
- They are also the first and to date the only villains to appear in six seasons and three movies.
- The Trix were locked in the Legendarium that Selina had and gave it back to Eldora.
- They were released in Season 7 by Brafilius unintentionally.
- In the episode "Acheron" the Trix say that no one double-crosses them, which is ironic since they have already been double-crossed by Darkar, Tritannus, Politea and Selina.
- According to what Icy says in Darko the Black, the Trix hail from a realm known as the Ice Kingdom, which remains unseen. The three witches spent their childhood in the Ice Kingdom and befriended a boy named Darko before they eventually left for Magix to become powerful witches.