Arnold Mackenzie

Arnold Mackenzie (アーノルド＝マッケンジ) is a background character referenced in Shinyaku Toaru Majutsu no Index. He is a young man whose gruesome death was used as a basis part of Hel's magic during her attack on an Anti-GREMLIN Alliance convoy en route to Tokyo, Japan.

Background
Arnold Mackenzie was 24 year old man, who at sometime in the past, was in a cruiser ship. He had an acquaintance aboard the ship as well, who questioned him about a romantic relationship. It developed into a fight and he was stuffed head first into the oven in the kitchen space. He died of shock due to the intense pain of burns all over his body.

It is unknown if he has any relation to GREMLIN member Freyja as Hel assumed.

Lance of Gungnir Arc
Analyzing the residual information of deaths in the sea near Saipan, Hel successfully discovers the cruel fate of Arnold Mackenzie and utilizes it in her magic. Using his death as a basis, she fires a bullet using a revolver at the ship, making it engulf in flames in the manner of Arnold's death.

The fires are later quelled by Silvia, the Saint who is a master of barriers.