Custodian (Stellaris)

The Custodians are robots created by the Human race to perform menial work and domestic services. Starting off as menial workers and personal servants, Custodians received gradual upgrades to their functionality as they were granted access to higher and higher echelons of Human society over time. Eventually, Humans became pampered dependants on the Custodians, who ended up assuming control over every facet of life on Earth.

Upon mastering space travel, the Custodians became driven to seek out intelligent life. Fearing that organic races will destroy each other without guidance, the Custodians decided they would serve organics whether they could be found, and protect them from each other and themselves if necessary.