Primagen or primogen are derived from "primogenitor", a word meaning the first or earliest ancestor. It may also be related to the word "primogeniture". The terms can refer to:
1. In fiction
- Primogen, the chief, and usually most powerful and eldest, representative of a vampire clan within a domain in Vampire: The Masquerade and Vampire: The Requiem
- Primogen Daishirou and Primogen Laenzuo, monsters in EverQuest II
- Primagen, a primordial alien monster, the primary antagonist and final boss of Turok 2: Seeds of Evil
- Primagen, a fictional species created in the "Furry Fandom"