Valtos is a lean built man with wavy grey hair that ends at the bottom of his head. He also has straight line going down each side of his face.
Valtos wears with a light colored hooded cloak, with black covering half the shoulders and down the middle. The cloak has three vertical eyes on the chest with sphere on the sides of each eye and on top of the highest eye. The design also has a line on the bottom most eye that makes it look like a key.
Underneath the cloak Valtos wears a tight black shirt with no sleeves and cut out beneath his chest. Black gloves that extends up to the upper arm. Black pants with two thin black belts.
During the Eye of the Midnight Sun's invasion of the Royal Capital, Valtos wears tattered shirts and pants, black belts that connects to a pouch that contains a grimoire, and a mask to disguise himself.
Valtos is loyal to Patolli and will disobey Patolli's orders to help him in battle. Valtos is also a calm person even when in dire situations, but will start to panic when Patolli is in trouble.
When Valtos was betrayed by Patolli, he spoke quietly in a depressing manner, only wanting to confirm the truth at that point. Without Patolli, Valtos is sulky and depressed, speaking quietly and slowly with his head always hung low, slouching and covering his face with his hair.
Outside of the Royal Capital, Valtos appears while Rades Spirito is talking to one of his corpses. Valtos tells Rades that everything is ready, and they commence their attack, during which Valtos disguises himself as a corpse and summons Rades's corpses as needed. After the Magic Knights spread out across the city and defeat the groups of corpses, Valtos activates Blackout, which teleports the knights to a spot hundreds of miles away.
After Fuegoleon Vermillion captures Rades, Valtos teleports the captain into a trap. Asta is able to sense him and drives him out. He then teleports Fuegoleon back, who is defeated and missing an arm. Valtos tries to teleport Rades as they finish their job, but Asta cuts through his magic, breaking his spell. Seeing Asta stop his magic, he decides to take care of him and starts preparing for an attack, but is then attacked and interrupted by Leopold Vermillion.
Several other members of the Eye of the Midnight Sun arrive to distract Asta and Leopold. When the stranded group of Magic Knights returns to the city, Alecdora Sandler confronts Valtos, so the Eye of the Midnight Sun members kidnap Asta and retreat.
When they arrive outside the hideout, Valtos tells Sally to kill Asta, but she refuses wanting to use him in her research. Upon entering, they are greeted by Julius Novachrono, who kills three of them and restrains the rest. Patolli appears and manages to rescue all except George. Later Valtos tells his master that George and Catherine will not leak any information, but Patolli is not worried about that and says that they will eventually rescue them.
When Sally receives an alert from Baro, Valtos sends her to the cave near Nairn. He later accompanies Patolli to the cave. After Patolli rescues Sally, Valtos takes her back to the headquarters and returns to help his leader. When he notices that Yami Sukehiro has arrived, Valtos asks if he should bring them, but Patolli says that he can handle Yami.
During the fight, Patolli tells Yami a story and Yami responds with one of his own. Valtos asks if Yami is making fun of Patolli, but Yami tells him to keep out of it. When Yami manages to cut Patolli, Valtos is surprised and says that Yami will pay. Valtos thinks about what Yami had done and wonders if Yami has the power to rival the Magic Emperor.
Valtos volunteers to help, but Patolli tells him to capture Asta. Valtos attacks Asta with a spell but it is blocked by Yami. When Yami tells Asta to battle Valtos and sense his attacks with Ki, Valtos says that Asta will not be able to sense his attacks and manages to hit Asta with a spell. Valtos attacks again but the spell is reflected back, hitting Valtos square in the chest. Angered over another of his subordinates being injured, Patolli destroys the cave and buries Asta and Yami. Valtos compliments Patolli for his power and is shocked when Yami and Asta pop out of the rubble.
When Yami and Patolli continue to battle, Valtos attacks Yami but is easily countered. Asta charges at Valtos, who creates multiple portals around the boy and fires several Magic Bullets through them. Asta reflects most of them back, but Valtos uses another portal to dodge. He continues the series of attacks until Asta cannot move. When Asta throws his swords away, Valtos says that Asta has lost it and prepares to fire another blast. Asta then jumps through a portal and punches Valtos, knocking him unconscious.
Months later, Valtos transports Sally, Rades, and an army of corpses to the Black Bulls base. While Rades and Sally fight outside, Valtos summons No.0 - Michael Caesal and then enters the base in search of the magic stone. He notices the base trembling but believes it to be due to the fighting outside. He breaks into Asta's room but is impeded when the whole base rearranges. Eventually Valtos retrieves the stone and returns outside. He demands that they leave at once. Rades refuses but Valtos will not let him put another mission at risk due to his selfishness, and the three Eye of the Midnight Sun members retreat.
After Patolli gathers the two stones from Julius, Valtos appears and they narrowly escape Yami's Dark Cloaked Dimension Slash. They then travel to the sephirot, which is within the giant skeleton outside Hage. Valtos celebrates as their plans are about to come to fruition, but before Patolli places the last stone, the elf reveals his hatred for all humans, including those within the Eye of the Midnight Sun. Shocked by this change in attitude, Valtos panics as the sephirot begins to glow. As the three humans' bodies begin breaking apart, Patolli reveals that the naming ceremony was for marking them as sacrifices. Valtos pleads with the elf, and the three collapse as their bodies burn and their mana is extracted.
Later, after Patolli leaves for the Royal Capital, Rades's magic brings him back to life. Seeking revenge, he also brings Valtos and Sally back to life, and the three teleport to the Black Bulls base. Rades offers to assist the Black Bulls if they help with his revenge, but Asta refuses and questions Valtos's and Sally's motives. Valtos simply wants to see Patolli one more time and is willing to cooperate as atonement. Charmy Pappitson then offers him some of Master Chef's food, restoring his magic power, and Valtos teleports the whole base to the capital.
After the Apostles of Sephirah summon the Shadow Palace, the base is warped into Clover Castle's courtyard and fights several elves. When the group of elves is defeated, Reve pulls part of the base into her Glamour World, while Patolli and Drowa combine magic to destroy the rest of the base. Gordon and Grey manage to cushion everyone's falls. Seeing Patolli fly off into the Shadow Palace's gate, Rades orders Valtos to warp the two of them over there.
After the devil is defeated, its magic does not disappear and instead threatens to swallow the Shadow Palace and everyone inside. Valtos saves a group of Magic Knights and elves and warps them up to the topmost chamber where the exit is. After the humans and elves return to Clover Castle, Valtos hands William Vangeance's grimoire to Patolli so that William and Licht can stop the still rampaging elves. After Rades resurrects and yells at Patolli, Valtos and Rades teleport away.
- Spatial Magic: Valtos uses this rare magic attribute to manipulate space. He can teleport instantly individuals or groups of people and use his magic portals to attack from any location.
- Magic Bullet: Valtos is capable of manifesting and concentrating his mana into his hand. Subsequently, he can launch the mana towards his opponent, blasting them away. He uses this ability mostly in conjunction with his portals, performing surprise attacks against his opponents.
- Magic Power: Valtos possesses a large amount of magic power, as shown when he activates five giant spatial portals simultaneously.
- Asta vs. Valtos: Loss