Primogen
Primogen is a term that denotes the firstborn child. It is derived from Latin primogenitus ("first-born") and is commonly used in discussions of inheritance, lineage, and social status.
Primogeniture is the system by which the firstborn inherits the family estate, title, or office. Variants include
Historically, primogeniture concentrated land and power in the eldest generation and influenced marriage, politics, and succession.
In fiction and popular culture, Primogen is used as a title for senior figures within a clan