Thomas Edison is a Caster-class Servant from Fifth Singularity, E Pluribus Unum. He is a leader of the American forces.

Fate/Grand Order: Turas Réalta:

Edison took control of the American forces left broken by the Celtic Army, founding the United Western States, anointing himself its President-King. He created the Mechanized Infantry, robots based on Charles Babbage's design, albeit powered by electricity. He also recruited Helena Blavatsky and Karna, with the former being an old friend. With their help and his robots, the Americans were able to even odds against the Celts.

Appears in chapter 37.

(Source: TYPE-MOON Wiki)