Aeacus is a semi-boss (particularly a main boss among the 3 judges of the Underworld). He, along with Minos and Rhadamanthys are known as the 3 Judges of the Underworld. Due to his distinctive Legion armor and dual Legion scythes, he is without doubt categorized to have sided with the Legion. His weapon of choice are the dual Legion Scythes.
Another version of Aeacus, known as the Ultra Aeacus is a reconsidered stronger version of Aeacus. Nothing is changed to its appearance, but its HP and its attack damages are far more greater than how Aeacus dealt. Its attacks are more smarter and it is recommended to attack through party (group) though it is possible to defeat him solo with the right class.
- Aeacus is based and inspired through the Greek Mythological figure, Aeacus, a demigod king and one of the 3 Judges of the Dead, along with Minos and Rhadamanthus.
- Aeacus' armor is similar to those of the Undead Champion Armor.