Eraqus

Master Eraqus is a character who appears in Kingdom Hearts Birth by Sleep as the master of Ventus, Aqua, and Terra.

Kingdom Hearts Birth by Sleep
In Kingdom Hearts Birth by Sleep, Master Eraqus is shown together with Master Xehanort, and opens the Master Qualification Exam for Keyblade Wielders and Apprentices. He's also the one who sends out his apprentices to search out Master Xehanort and Vanitas after their unexpected leave. Since the Unversed mysteriously started to appear at the same time as their leave, Master Eraqus sent Terra and Aqua to see if there was any connection between the two events.

At the beginning, of Kingdom Hearts Birth by Sleep, he holds the Master Qualification Exam for Aqua and Terra. In the end, he passed Aqua and fails Terra on the grounds that he is unable to control his darkness. Unknownst to him, Master Xehanort appears to have been behind some of the darkness that was shown during the exams.

Shortly afterwards, Eraqus sends Terra out on his quest after hearing from Yen Sid about the Unversed.

Sometime after Terra's departure, he warns Aqua to look after Terra for he fears that Terra might be tempted by the darkness.

He also attempts to kill Ventus at some point towards the end of the game. This is because Ventus and Vanitas have the ability to create the X-Blade, a Keyblade with the ability to return all worlds to darkness. During his attempt, Terra arrives and defeats Eraqus using his darkness before Master Xehanort finishes Eraqus off.

It has been hinted in the Secret Ending, that his heart was passed on to Terra.

Appearance
Master Eraqus, like his student, Terra, bears a distinct Japanese influence in his choice of clothing. He wears a white, red lined haori that seems to have a hood, along with slightly shorter than normal, light-colored hakama. Underneath his haori, he wears a navy blue shirt with a large white X pattern on the front. He also has a jagged scar over his right eye and on his left cheek (the latter being quite similar to Braig's scar).

Like his pupils, Eraqus wears pieces of armor, in his case gold and black armored boots and a dull blue-green section that covers his abdomen. This second piece of armor sports the same symbol worn by his students near the top. Eraqus's black hair is tied into a short, high topknot, with one bang falling off to the right side of his face. He also has a short, triangular soul patch and a mustache.

Weapon
Master Eraqus wields a rather basic Keyblade, gray in coloration. It has the appearance of an old fashioned skeleton key, the tip being shaped like an "E", the first letter of his name. Interestingly, its keychain is the symbol that Aqua, Terra, Ven, and Eraqus himself all wear in their clothing.

Trivia

 * Master Eraqus wears a similar belt like Terra, Aqua and Ven.
 * Master Eraqus resembles and could be possibly be based on the appearance of Hironobu Sakaguchi, the creator of the Final Fantasy series.
 * His name is an anagram of "Square", the first name of the series's developer. This trend is based on Yen Sid's name being the reverse spelling of "Disney", the other company who produced the series.
 * Tetsuya Nomura stated the relationship between Master Eraqus and Master Xehanort is something like old classmates.
 * Master Eraqus, Braig (as well as his Nobody, Xigbar) and Saïx are thus far the only characters in the series who have received permanent and visible body damage.
 * Master Eraqus received his scars after a confrontation with Master Xehanort.