The Eye of the Hunter (狩人の眼 Karyūdo no Me) is an ability possessed by the heir of the Terumi branch of the Amanohokosaka Clan. It allows the user to see the life-force value of any individual. Naoto Kurogane is its current possessor.
This ability allows the user to see ancient characters above a person's head which numerically represent that person's life-force value. The higher the number, the more 'life' a person has. Typically, having a higher life-force value means that someone is happy or strong; most Drive users have a high number. The lower a number, the closer someone is to death, with hospital patients having a little over 1000, and the deceased having 0. When a person dies, the possessor of the Eye can see a form of black noise consume the corpse.
While this ability is similar to a Drive, it does not fall into the same classification. Saya Terumi desires the Eye of the Hunter as proof of being the heir to the Terumi clan. Her obsession extends to wanting to kill her own brother just to obtain it. 
- Clavis Alucard - immeasurable
- Raquel Alucard - 10,000,000; formerly 80,000,000
- Valkenhayn R. Hellsing - 2,394,211
- Haruka Hayami - 10,500 - 10,512
- Relius Clover - 9,152
- Kana Kirishima - 9,006
- Saya Terumi - 7,946; constantly fluctuates because of her Drive, Soul Eater, which consumes the life-force of others.
- Naoto Kurogane - 0; formerly 9,810
- Tadayuki Isa - 0; formerly 925 - 1,007
- Rachel Alucard - has no number