Wendy

Wendy is a witch who attends Cloud Tower. While she never makes any physical appearances, she is only mentioned in Issue 55 of the Winx Club Comic Series as a victim of kidnapping.

Season 4
In the very beginning of Temptations, a commotion occurs within Cloud Tower's walls once Magix City Police arrive and search one of the student dorms. Shortly afterwards, Griffin begins shouting over such a case being "absolutely unacceptable," and it is later revealed during a conversation amongst the Winx that a girl named Wendy had disappeared.

Stella quickly latches onto the idea of Wendy running off to elope with a boy until Musa reveals that all signs of Wendy's disappearance point to her having been kidnapped in the middle of the night. Since Wendy's parents are not notably wealthy, there were no signs of a ransom note, but it still begged the question as to why she was suddenly taken in the first place.

Musa then goes on to advise the girls to be careful as she suspects that Wendy may have been forced into a magical trafficking ring; one that would force young girls into creating "terrifying magic filters." Stella plays with this idea by claiming that such filters require the hearts of young witches and advises for Flora to stay close to Helia so that he can keep her safe.

By the end of the issue, after Riven rescues Musa from a gang of kidnappers, the Magix Police Chief commends Riven for his actions as the men who almost got away with kidnapping Musa were the last remaining members of the trafficking ring responsible for kidnapping Wendy a few days prior.

Magical Abilities
Like all witches, her powers are derived from the negative aspects of magic. Wendy may know some basic, first-level spells that all witches can use, such as telekinesis, transmuting objects, and fixing minor messes. Like all witches, she can fly.

Trivia

 * The name Wendy is a feminine English name derived from either the Welsh name, Gwendolyn, or the originally Polish name, Wanda.
 * It is unknown as to whether Wendy had been found and rescued by the Magix Police Force or, remained trapped within the magical trafficking ring she was forced into.