Witch Forms are different forms that witches can obtain to strengthen their sinister abilities.
A witch's magic, though limited while in her civilian form, is more effective than that of a fairy's. Many witches can even use the full extent of their powers without having to tap into another form, thus making the various witch forms a rare occurrence.
Unlike fairies, who acquire higher-leveled forms as they mature, witches only seem to be able to gain new, more powerful forms through primarily external means such as charms and hexes.
In Winx Club, the Trix have attained up to five different witch forms, in addition to their basic witch form. In the Winx Club comics, a witch from earth named Jenny Carter, is the first witch that isn't part of the Trix to have a witch transformation shown.
These consist of the only known forms that a witch seems to be capable of attaining without the use of outside influences.
In Season 1, the Trix showcased the ability to change out of their civilian attire to this form, which also served to amplify their respective powers. Not much is known of this form, as many other witches are able to use their own magic without undergoing a similar transformation, but it could also be possible that this is exclusive to the Trix themselves.
The Trix are seen switching to this form again when they attack the beginning of the year ceremony at Alfea to steal the magic compass which would allow the Ancestral Witches to find the Pixie Village. This time, they are seen transforming into their witch forms through a blast of lightning conjured by Stormy.
In Season 6, the Trix will themselves into this form upon their second takeover of Cloud Tower through a mysterious pack of crows or cravens. It is unknown how the Trix manage to do so but, through this form, their powers are amplified and they gain the ability to teleport by splitting themselves into a flock of crows/cravens made from their magic. It should also be noted that this form has no official name, and is only referred to as "Dark Witch" for convenience.
These consist of the multiple forms acquired through magical items, powerful spells or a foreign power source.
- Main article: Gloomix
In Season 2, the Trix are bestowed with the power of Gloomix by Lord Darkar, the Shadow Phoenix, upon being freed by him. As dark charms created directly from Darkar's magic, the Gloomix form acts as a significant booster to a witch's powers, even allowing for one to use her magic in anti-magic zones like the Wildlands.
- Main article: Disenchantix
Much like the powers before it, Disenchantix acts as an amplifier for each of the Trix's specified powers, but it also speeds up their recovery time (possibly through enhanced regeneration), allowing for the trio to withstand even the more powerful spells in the Winx's arsenal and attack as if nothing happened.
- Main article: Sirenix (Form)#Dark Sirenix
During the Winx's search for the fabled Sirenix form in Season 5, the Trix, alongside Tritannus hunt down and kidnap Daphne to get this ancient power before the Winx. After Tritannus strips Daphne of her own Sirenix powers, he a corrupted form of Sirenix to the Trix.
Apart from the form's more sinister appearance, not much differs between this and regular Sirenix, as both bestow their users with the same abilities such as access to the Infinite Ocean, the ability to breathe, swim faster and use their powers more effectively underwater.
- Main article: Shape-Shifting Witch
Following their sudden return in Season 7, the Trix, upon finding the source of all Wild Magic within the Magix Underground World, absorb some of the pure Wild Magic and merge with their bonded animals; all of which resulting in this new form.
As the name implies, the Trix, as Shape-Shifting Witches, can freely shift between different appearances; mainly those of magical animals. Their magic is also amplified to a greater degree thanks to both the Wild Magic they absorbed and the magic they most likely gained from fusing with their bonded animals.
In Star Shattered, an earthly witch named Jenny Carter is shown to transform to a witch attire that looks nothing like the Trix's first witch form. Its possible this can be a witch form for earthly witches to earn. Not much is know about this witch form except that it is most likely a first witch form that, witches can have.
This witch form consists of a black dress with a low cut at the chest, and has one strap. A smell magenta infinity cloth is worn around the neck and arms. Where the knees would be there is an A-shape by magenta ruffles, and in this form Jenny Carter, is also bare foot in this form.
- It is unknown if Gloomix, Disenchantix and Dark Sirenix are actual forms witches can earn, or if they were created for the sole purpose of giving the Trix powers suitable enough to counter the powers of the Winx.