Arnold Beckman (アーノルド・ベックマン, Ānorudo Bekkuman?) is the secretary to the director of Seraphix, a division of the Chaldea Security Organization. During the incident after Zepar merges with Kiara Sessyoin, he is the last survivor.
Beckman is an extremely unpleasant person, expressing contempt and ingratitude towards Fujimaru and their servants despite being saved by them. He took to using poison to execute any survivors of the Seraphix Incident who disagreed with him, and may have never bothered to learn Mable Macintosh’s name (though the ambiguity of her existence because of Kiara’s impersonation makes this unclear).