Iscarius was an Intelligence Army Warrior Beast who was the briefly featured Monster of the Week on episode 25 of the Great Mazinger Anime serving under the command of Marquis Janus, this episode also mark the introduction of Shiro's Robot Jr. in the anime. His appearance resemble that of a hunchback armored warrior, wearing a brown helmet with a sharp blade, a light and dark gray huge, with dark abdomen and black belt, with Brown arms, grey hands and legs, and blue and black boots with brown straps. His real face was located in the buckle. His only known abilities were extended arms, likely super strength, and the tentacles on top, which he could use to whip his enemies or restrain projectiles.

After the damage sustain with battle with Pharabos, the Emperor takes the chance to attack while Tetsuya and Great are out of commission and sends out Marquis Janus. As Shiro begins training with Robot Jr., she attacks with a barrage of missiles, and the Science fortress submerges and activates the shield, a still wounded Tetsuya tries to deployed but is stopped by the Jun and the Staff.

Shiro gets the Borot gang, who with their new Bombs (which serve as both weapons and Borot's new propulsion system – To be fair, they pop like fireworks) and take off to the Volcano Missile Island to attack. When they arrive, they are received by Janus herself and Iscarius. Borot's bombs have no effect on the Beast, Kabuto finds out of Borot and Jr's dilemma and deploys Venus A to rescue them. When she arrives, Iscarius disposes of the Robots, and crushes Borot into a ball, and throw it onto Venus, crashing. The beast thus the same to Jr and throws him at Venus. As the 3 Robots are pinned down, the Science fortress arrives to assist – Tetsuya finds out of the trio's problems, in the argument, he learn of the Professor's is father to Shiro, which forces him to go out to deploy Great, despite his wounded state.

Great finds the Robots and gets a message from Janus, threatening to sink the island, drowning his his friends, if he did not surrender. Tetsuya reacts by throwing the Great Boomerang and cuts Iscarius in half, and fires his weaponry onto the Missile Base, causing damage to missile silos. Janus orders to sink the island, Jun rescues Borot, while Great save Robot Jr. As the Robots escape Janus vows revenge, while a relief Professor Kabuto comes to terms to reveal his true identity to Shiro.

Iscarius was among the SuperHuman Beast dropping from the Mikelos Warship in the opening sequence of Final Countdown in the OVA Mazinkaiser vs the Great General of Darkness Deathmatch. His fate afterwards is unknown, as he did not form part of Dante's group of surviving Warrior Beasts in the ruins of the Photon Power Lab.