Treant

The Treants are the legendary/magical creatures appear in Season 6. They are voiced by Matt Shively, Charlie Schlatter, Dee Bradley Baker, Bryton James and David Faustino.

History
Not much is known about the history of the Treants, but according to Selina and her Legendarium, the Treants were described as "ancient knights who took the shape of huge trees", implying that they must've existed for centuries. However, as confirmed by Miele, the Treants were always good-natured and never evil. Miele also mentions that they are human trees. According to Flora, the Treants were full of life in just a single touch.

Season 6
The Treants get summoned by Selina via the Legendarium in "The Flying School". She ordered them to attack Lynphea College and proved to be too powerful to be defeated by the Winx, Flora's sister Miele and her friends, the Specialists and Sky's cousin Thoren and his friend Nex, who are both Paladins.

In the next episode, the Treants continued to attack the college, but later, they were freed from the evil spell by Flora, using her new Bloomix powers.

Appearance
They have shapes of huge trees (as the story) with branches on their head and two branches in two sides of each one as hands. They can walk on their roots (if they awake). Their eyes are red and evil (because they are ordered by Selina via the Legendarium) and they have beards and faces of elderlies.

Trivia

 * In Season 4 the Amazon Fairies used their magic to turn trees of the Amazonian Rainforest into humanoid Treant-like creatures.
 * It is unknown if their eyes are red and evil when they're normal like when they are ordered by Selina via the Legendarium.