Kayneth Archibald El-Melloi

A nobleman and a renowned mage from the Magus Association, Kayneth was a prodigy among magi, possessing exceptional magical potential and skills. He held the title of Euryphis lecturer within the Clock Tower, a notable mage academy, despite his young age. His magical lineage, going back nine generations, further enhanced his status. His magical abilities were attributed to wind and water, and he is proficient in the magical arts of summoning, alchemy, and spiritual evocation. He is also a teacher of Waver Velvet's, and was responsible for rejecting and tearing up Waver's radical thesis concerning magical potential. This act was in turn directly responsible for driving Waver to, in retaliation, enter the fourth Holy Grail War by stealing a valuable artifact from Kayneth.

Lord El-Melloi is, with regard to magical ability, arguably the most skilled Master in the Fourth Holy Grail War. He excels in magic involving mercury, which he employs to create a variety of attack and defence forms, such as barriers strong enough to resist point blank Claymore Mine blasts and flying blades capable of slicing through stone walls. Lord El-Melloi's mastery is great enough such that his enchanted mercury can react without his conscious control, automatically forming shields against surprise attacks. Kiritsugu Emiya initially regards Kayneth as one of the two most threatening magi involved in the war alongside Tokiomi Tōsaka, though neither are considered the most dangerous to be involved.

He's engaged to Sola-Ui Nuada-Re Sophia-Ri, the daughter of the head of the spiritual evocation division, through an arranged marriage. While Kayneth is in love with her, Sola-Ui despises Kayneth, considering him a coward for not attacking opposing Masters face to face.

Kayneth is the Master of Lancer in the Fourth Holy Grail War. His participation in the War is merely a bid to increase his own prominence within the Magus Association. His initial base of operations was located at the Fuyuki Hyatt Hotel, and protected by twenty-four layers of barriers, numerous summoned monsters, various traps, and mystical spatial alterations in the lobby.