Ellis Warrior

Ellis Warrior (エリス＝ウォリアー) is a posthumous background character referenced in the Toaru Majutsu no Index series. He was the first attempt at creating a Magician-Esper hybrid.

Background
Ellis was an esper 20 years ago before the start of the series, indicating that the Power Curriculum Program and espers already existed at that time. He was chosen by Academy City to be part of the joint institution created by a secret cell within the Anglican Church whose goal was to create a magic and esper hybrid.

A young Sherry Cromwell was assigned to teach Ellis magic, and they became great friends. However, when Ellis tried to use magic, the contradictions between magic and AIM proved fatal for him, bursting his blood vessels and severely injuring him. A moment later, operatives of the Knights of England came and destroyed the institution that Sherry and Ellis were in under the pretext of preventing the leakage of magic teachings and secrets. The higher-ups of the Anglican Church, who found out that the institution was in contact with the science side, didn't want magic to have any contact with science. The knights then bludgeoned Ellis to death with maces as he bought Sherry enough time to escape.

The event forever traumatized Sherry, who would later dedicate her magic name and the name of her golem in memory of him.

Kazakiri Hyouka Arc
Sherry Cromwell infiltrates Academy City in order for her to separate magic and science, with the most desired outcome being war between the two sides. Here, she uses a golem she named after Ellis to cause damage, using her magic name dedicated to him.

Sherry later tells Touma about the real Ellis's fate as a hybrid between the two sides just before Touma defeats her.

Agitate Halation Arc
Ellis is mentioned in this arc to emphasize the fact that espers cannot use magic. His last name is revealed to be Warrior.

Lance of Gungnir Arc
In the final recreation of the world by Othinus created specifically to break Touma's spirit, known as the Version_Omega world in-text, where several characters from the original world have been "saved" or have not experienced great tragedy, Ellis and Sherry are the first people Touma sees in this reality. Here, Touma is utterly stunned by Sherry calling out to Ellis, knowing that he was the deceased friend that Sherry mentioned to him before in the original world. Here, Sherry is trying to catch up to Ellis who ran ahead of her. For some reason, the both of them are children, while every other character is presumed to be of the proper age.