The Mark of Valtor is a sinister magic spell and namesake icon created and used by the wizard Valtor in the Winx Club universe. It is also his trademark. The symbol looks like a transparent "V" with purple borders.
He puts his accursed 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 servers, 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 the Cloud Tower when he made it disappear towards the end of Season 3, and above Magix when he created a magical image of him in the sky to challenge Faragonda, Griffin and Saladin to fight against him. This will need Fairy Dust or the Mirror of Truth to break the Mark's spell so they can be released.
- The Mark of Valtor has some similarities with the Dark Mark of Lord Voldemort (recognized and revered by the Death Eaters) in the Harry Potter series, in the sense that in both cases their respective marks were put on their servers, 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, they left the V in his mark alone.