Dalton Strauss (ダルトン・ストラウス, Daruton Sutorausu) was Renee Paramedes Branvillier's alchemy teacher and the headmaster of the Third Library in Lotto Valentino. He is also one of the three surviving pre-1711 immortals, along with Renee and Archangelo, before the generation of the Advena Avis.
In 2003, Dalton serves as the Third Library's head librarian and manager.
Dalton is an elderly, white-haired man with a long beard and mustache, who carries himself more like a warrior than an alchemist. He often wears a wide-brimmed hat atop his head in the 1700s, as well as a wooden right arm - which he briefly replaces with a metal hook at the request of one of his students (who thinks Dalton looks like a pirate). He switches back to his wooden arm once it is repaired.
In 2003, Dalton's prosthetic is much more realistic.
Dalton's greatest priority is his scientific research; not being able to see it to the end is a greater source of fear than the unknown after death. Unlike Renee, he is capable of recognizing when he fails to act morally. He admits that he immersed himself in his research to avoid thinking about his students devouring each other, and confesses that he taught Huey's group the secrets of immortality as an experiment.
Dalton was one of ten individuals who became immortal at the same time, five hundred years ago. After ten years of peace, the group turned on each other out of fear of death, greed, and experimentation, until three were left. He agreed to replace his right arm so that Archangelo would not devour him as a potential threat to Renee.