Although you have given no other context, I assume that your text has to do with Mythology in various cultures. Assuming this is correct, I can say the following:
Ιn numerous cultures it is customary for old women to take care of the dead by dressing, anointing and watching over them until the funereal rites are completed. Such a woman is represented as the Goddess of death: Crone. As the bringer of death the Crone is also the ultimate judge. Other names of Crone or bringer of death, depending on the culture, are the Dark Mother Kali, the Hindu Goddess of Life and Death. Kali's titles include Shyama - the Black One, Chandi - the Fierce One, and Bhairava - the Terrible One, and it is in these forms that she receives blood sacrifices, usually from male animals.

Kali is commonly depicted as an animal, a towering black-skinned Goddess whose tongue stretches from her blood-dripping mouth. She is heavily garlanded with serpents and skulls. Her skirt is made of severed arms and hands of evil-doers. She brandishes a sword in one of four hands while another hand holds the decapitated head of the demon Mahisa (who at one point threatened to destroy the Gods and humanity).

We find Kali in ancient Crete as Rhea, the Aegean Universal Mother Goddess who was worshipped over a vast area by many different peoples.

Sorry, forgot to add the word-for-word translation of bringer of death, just in case that's what you want to use... I should note however that I have never encountered this as an animal name. The only thing that comes to mind as the name of an animal who is a bringer of death is "Κέρβερος", Death's ("Χάρος" in Greek) dog in Greek mythology. Just an alternative to my previous answer. But again, this is not the literally translation of your phrase
Hope this helps

The second answer seems the best. (I am trying to help you). The only animal I can think of is a snake or the like. There is no to my knowledge animal that can cover this. Besides Greeks were lovers of nature, I cannot imagine any living creature to be called that. Also Greeks comprehend death, and therefore, they do not feel afraid.
I am a Grecian Greek

Άγγελος θανάτου = agelos thanatou = death angel (in Greek angel=messenger)

This is the most common use