Master Eraqus is a Keyblade Master featured in Kingdom Hearts Birth By Sleep. He is the master of Terra and Aqua, and he also serves as the second master of Ventus.Master Eraqus is a strong Keyblade master, caring very deeply for his three apprentices, Terra, Ventus, and Aqua. Stern and willing to instruct, one major goal he has in life appears to be preserving peace throughout the worlds, as he rashly attacks Ventus when Eraqus discovers that through his dark half, Vanitas, Ventus can create the X-Blade, the weapon that sparked the Keyblade War and that Master Xehanort desires.

He also feels strong attachments, having Aqua look after Terra, whom he sees as a son (and whom also considers Eraqus as a father figure), as he travels the worlds, apologizing before his assassination attempt on Ventus, and even shedding a tear when he is forced to face off against Terra. Eraqus has a strong sensitivity to betrayal, having experienced it far too many times in his life, both at the hands of Master Xehanort and Terra, himself.Master Eraqus appears as a boss in Terra's storyline after the Keyblade wielder rescues Ventus from an attempt by Eraqus to kill him, and Terra is forced to fight him. During battle, Eraqus uses many quick lunging attacks, and is able to land many hits before the combo finisher. He also has several desperation attacks, each based on the light element.Master Eraqus wields a rather basic Keyblade, grey in coloration. It has the appearance of an old fashioned skeleton key, the teeth shaped like an "E". Interestingly, its Keychain is the Keyblade "Mark of Mastery".