Tiberius Kirk
Tiberius Kirk was the father of George Kirk and the paternal grandfather of George Samuel Kirk and James T. Kirk. His name was the source of his grandson James Tiberius Kirk's middle name. 

In the alternate reality, his given name was suggested by his daughter-in-law, , as a first name for their .  disagreed with the choice, and opted to have his son named after his father-in-law,  ()

Appendices

Background information 
John M. Ford's Pocket TOS novel How Much for Just the Planet? () previously established that "Tiberius" was handed down from James Kirk's great-grandfather.

The idea was also included in the first draft script of , in which he was given the full name "Tiberius Edmund Kirk". Also in that script, Benjamin Sisko started saying, "[He] was one of the first men to climb the…" though Jadzia Dax then interrupted Sisko.

Apocrypha 
According to writer Christopher L. Bennett, author of the Star Trek: Enterprise - Rise of the Federation series of novels, Tiberius is supposed to be the son of 
, a historian that served on the  and , the armory officer of the USS Pioneer.

In the  , Kirk was referred to as "grandfather Samuel" by his grandson James. The novel also reveals that James learned the swear word "Shit" from his grandfather. 

According to the Pocket TOS Provenance of Shadows novel, Tiberius died in 2238.

According to The Autobiography of James T. Kirk, Tiberius was in his 20s when Starfleet Academy was formed and that he applied but wasn't accepted. Still wanting to get out into space, he signed on in Ordnance and supply and served on several starbases until getting assigned to  where he met and married a nurse, . Their son, George Kirk was born there on December 13, 2206. Tiberius had hoped that George would go to Starfleet Academy but admission was very competitive. That dream was later fulfilled when Tiberius was awarded the Starfleet Medal of Honor for rescuing five men after Starbase 8 had suffered an explosion on the loading dock. Despite Tiberius being an enlisted man, the children of Medal of Honor winners were given high priority during the admissions process.

External link 
 

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Humans