So far we've seen very little of Thanos' presence in the MCU other than references to him in Avengers and a minor appearance in in GotG. He seems to just be floating around in his asteroid field, but his name is certainly known to most of the people and races we meet in Guardians. He obviously has a level of influence over the Chitauri race, or at least their soldiers. But what about his people?
In the comics, he's an Eternal - an offshoot of Earth humans influenced by the Celestials (Knowhere head). So far no mention of the Eternals and it doesn't seem like Thanos has any connection to Earth or Humans in the MCU. So where are his people and what has he already done that makes him so well-known?