Prime Eternal

Prime Eternal (also known as Prime One) is the title of the leader of the Eternals of Earth. It is usually (but not always) the Prime Eternal who initiates the ritual of the Uni-Mind.
Prime Eternals are usually selected by an election held within a Uni-Mind, with the candidate who receives the most votes being chosen. However, in recent years, Thena inherited the position from her father Zuras after his death and Ikaris took the position and power from Thena by defeating her in mental combat in the Hall of Eternal Judgment. It should be noted that these two transfers of power took place during a time when the minds of the Eternals had been altered so that they were unaware of the fact that they normally resurrect if killed and the death of Zuras was believed to be permanent.
The position of Prime Eternal did not exist during the Age of the Patriarchs, that period in Eternal history before Uranos was excluded 600,000 years ago. It has not yet been revealed if the position was created before or after Kronos was excluded 500,000 years ago.