The Ak'Haireth or Bone Drinkers were an alien species in the 30th Millennium.
Parasitic sentient lifeforms who operated in psychically interwoven gestalt called Blooms. They sustained themselves by slowly feeding on any animal life. Their favorite prey was humans as the bone marrow was a delicious target for them.
The Ak'Haireth were a fungoid species that opposed the Imperium of Man during the Great Crusade. They operated at the edge of Segmentum Solar, inhabiting scavenged ships and raiding isolated colonies. Despite the numerous genocidal campaigns by the Space Wolves and Night Lords, the aliens were resilient and able to always return. The aliens were wiped out of existence during the Hunting of the Ak'Haireth, in which Alpharius and the Alpha Legion deployed a deadly biological weapon and drive the species to extinction.
- The Horus Heresy Book Three (2014)