Mark of Valtor

The Mark of Valtor is the trademark/brand of Valtor.

Appearance
It is a transparent V-like shape, styled as a demon face/skull with 2 horns, with purple borders. The mark glows in lighter purple. In season 8, the mark's color changes to red/crimson.

When marked on the victim's body, it might appear in different colors like red, black, brown, etc.

Season 3
He puts his mark on magical creatures for various reasons. He placed his mark on Countess Cassandra and Chimera when they became his allies, but he also used it on other people to make them become his servants, like he did to the mermaids of Andros, which he also turned into mer-monsters. His mark also appeared on Sky's shoulder and on Radius's neck when they were under the control of Diaspro and Cassandra respectively.

His mark also appeared above Cloud Tower when he made it disappear towards the end of Season 3, and above Magix when he created a magical image of himself in the sky to challenge Faragonda, Griffin, and Saladin to fight against him.

Season 8
The Winx (Group) discover the mark of Valtor on one of the Golem Monsters they fought in Winx Club - Episode 802.

Trivia

 * The Mark of Valtor has some similarities with the Dark Mark of Lord Voldemort in the Harry Potter Series, in the sense that in both cases their respective marks were put on their servants, and that they were used as a way of signing something they had recently done which would help them to victory.
 * The Mark of Valtor is similar to the Irken Empire's logo from Invader Zim.
 * Even though 4Kids changed Valtor's name to "Baltor", his mark remained shaped like a V.
 * A blue V-shaped mark without demon face/skull appears when Valtor activates the Water Stars Catcher.