A tahedri (plural: tahedrin) was the senior male or patriarch of an Orion family. He was a counterpart to the tabadi, or matriarch.

The tahedri was the dominant authority figure in the family, respected for his age and position. He decided how members conducted themselves, arranged marriages, found jobs for the sons, found husbands and dowries for their daughters, organized care for the sick, and ran the family business if they had one.

A retiring or dying tahedri appointed his successor, usually his eldest son or otherwise the oldest, most closely related male family member, preferably from amongst his descendants. However, depending on the size of the family and the capability of the immediate candidates, he could instead appoint a woman, a younger person, or even multiple replacements. However, no matter the respect for the previous tahedri, almost every new leader abandoned his predecessor's plans and style and chose a new path.

A tahedri took pride in a happy, healthy, prosperous, and unified family. Such a state did not come easily; maintaining a family over the generations meant never-ending struggle, compromise, and continual readjustment against constant changes. Most importantly, news of internal conflict could never reach the ears of outsiders. In divided families, members plotted to get around a still-respected tahedri's commands. In the worst and rarest cases, children rebelled against parents, and even violence broke out. However, one’s own family was the very last place an Orion could expect to be betrayed. (FASA RPG modules: The Orions: Book of Common Knowledge, The Orions: Book of Deep Knowledge)