Zanoba Shirone

The third prince of Shirone, he is impulsive and cares a lot about dolls to the point of disregarding human life. He has utmost respect towards Rudeus his master. Although he used to think of other humans as nothing more than dolls made of flesh, after meeting Rudeus, he slowly accepted other people.

When he was three years old, he killed his brother Julius, the fourth prince. At age 15, he killed his wife during their honeymoon. Because of his brutal strength and killing as if his victims were dolls, he obtained the nickname "Head-Ripping Prince."

He later becomes the lead developer along with Cliff Grimoire in creating a prosthetic arm dubbed "Zariff's Prosthetic Arm." They later research and invent more mechanisms such as developing magic armor for Rudeus. Zanoba also helps Rudeus in his Ruijerd doll-making business, even buying a dwarf girl slave named Juliette to hasten the task because his monstrous strength is not capable of making delicate details on dolls.
(Source: Mushoku Tensei Wiki)