Magnius was one of the Grand Five Cardinals and an antagonist in Tales of Symphonia. He was in charge in the Palmacosta Human Ranch. He was voiced by Shinji Kawada in Japanese and English Dubbed by Chris Edgarly.

In the past, Magnius killed Dorr's father and infected his wife with a seed that made into a monster. While Dorr was next in line on becoming a Governor-General, he and Magnius made a deal. The deal was that Dorr would unofficialy stop fighting the desians and to give the ranch a large amount of gald in exchange for finding the medicene to help his wife; however, the medicene didn't exist.

The group first saw Magnius trying to execute Chocolat's mother for her defiance against the desians by refusing to sell them any supplies. However, the party went against Raine's advice (about her fear of a "second Iselia") and decided to rescue Chocolat's mother from Magnius. He recognizes the wanted criminal, Lloyd Irving and rejoiced about capturing him in order to be promoted to being the leader of the Grand Five Cardinals. He ordered his men to capture the party and teleported back to the ranch due to an injury.

Later, Magnius contacted Dorr to help set a trap for Lloyd and Colette and had troops take the pilgrimage travelers prisioners, including Chocolat herself. In the control room, Magnius informed Chocolat that Lloyd killed her grandmother, Marble, due to her being a "monster" too. While Chocolate was enraged, she got captured again and Magnius began to fight the group. At the verge of his death, Kratos tells him that he is a fool and tells him that the Chosen was actually accepted by Cruxis and that she shall not be killed. Magnius realized that Rodyle tricked him into thinking that the Chosen had to be killed. Before the ranch self-destructed, Magnius tried to warn Forcystus, but was cut off by a hologram of Rodyle and then he dies in the explosion.