- Class: Gene Driver
- Gender: Male
- Age: Unknown
- Weapon: XERD_002GC "Gunclaw"
- Voice Actor: Masahiko Tanaka (Japanese), Dan Woren (English)
Hauser Blackwell (ハウザー・ブラックウェル), also known as The Black Reaper, was a soldier for the Global Union during the war. While he was considered a hero during the war, he was sentenced to over 4,000 years in prison when the war was over in a trial which he did not attend. He gained the skills of a Gene Driver through the experiements of the ARMs researchers.
The party first meets him at the Autumn River. As they travel the riverbank, Gawn speaks of the man he's searching for and why he's looking for him. This is where it's revealed that Raquel's hometown, Verklarung, was destroyed ten years before the start of the game — at the end of the war — and that there were few survivors. Many thought that Hauser hadn't survived the incident either. He was also thought to be the cause of it.Near the end of the river, a puppy is seen floating down stream in a box. Jude uses Accelerator to rescue the puppy, and loses his footing when he reaches land. As he's about to fall in, Hauser grabs his arm and pulls him forward. Upon shaking hands, Jude gets a vague glimpse into Hauser's memories involving the incident at Verkalung. There are two more occurances of Jude witnessing Hauser's memories later in the game, with information getting clearer each time.
He's seen again later in Verklarung, where he asks Yulie to exorcise the souls of the earthbound dead from the incident that happened ten years before. Jude, Raquel, and Arnaud catch up to them, and shortly after Gawn and a group of soldiers show up to arrest Hauser and bring Yulie into Brionac custody. While Yulie is kept on the Garra de Leon, Hauser is transferred to Illsveil Prison, where Lambda convinces him that humanity is the reason there is war.Having merged with the Divine Weapon, Hauser serves as the final boss in the game and has three forms. The first form heavily resembles him, but the last two grow bigger, increasingly monsterous, and no longer look like him at all. Once the party beats him with a final Arc Impulse, Jude thanks him for all he's done for the world and the future and tells him it's time to rest.
While it's never outright stated, it's heavily implied that Hauser is Jude's father. This would explain Jude being a natural a gene driver — assuming he was conceived after the experiments were performed — and their shared ability to use Accelerator. They also share several physical features, and whenever Jude has any sort of physical contact with him, he is able to get a glimpse of familiar sights in Hauser's memory, including those of Ciel Shelter and exchanges between Hauser and Jude's mother Ethelda.