TIL: The rarest blood in the world is Rhnull which is also dubbed "golden blood" and is shared by less than 45 people on Earth. It was discovered in 1961. It can be used by anyone even those with other rare blood types in the rh system and is extremely valuable with only 9 donors.
https://www.discovery.com/science/Rhnull-Rarest-Blood-Type-on-Earth
