Number One (Star Trek)

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Una Chin-Riley "Number One"
Star Trek character
Majel Barrett as Number One in the rejected 1965 pilot for Star Trek: The Original Series, "The Cage"
First appearance	Majel Barrett: "The Cage" (1965) "The Menagerie" (1966) (The Original Series) Rebecca Romijn: "An Obol for Charon" (2019) (Star Trek: Discovery)
Created by	Gene Roddenberry
Portrayed by	Majel Barrett (1966) Rebecca Romijn (2019–present)
Voiced by	Rebecca Romijn ("Those Old Scientists")
In-universe information
Full name	Una Chin-Riley
Nickname	Number One
Species	Illyrian
Gender	Female
Title	Lieutenant commander
Position	USS Enterprise executive officer
Affiliation	United Federation of Planets Starfleet

Una Chin-Riley, commonly and originally only known as Number One, is a fictional character in the science-fiction franchise Star Trek. She is Christopher Pike's second-in-command during his captaincy of the starship Enterprise.

She first appeared, portrayed by Majel Barrett in "The Cage", the initial 1965 pilot episode of the original series. The pilot was rejected and most of its characters, including Number One, were omitted from the second pilot and the subsequent series (the relationship between Spock and Kirk would emulate that of Number One and Pike).^[1][2] Footage from "The Cage" featuring the character was reused in the two-part story "The Menagerie" in 1966, establishing Pike and Number One as members of a previous crew of the Enterprise and part of the Star Trek canon; Barrett herself, who would become the wife of Star Trek creator Gene Roddenberry, would portray a number of unrelated characters in the franchise from 1966 to 2009, such as Nurse Christine Chapel in the original series, Lwaxana Troi in Star Trek: The Next Generation, and the voice of the Enterprise computer for both series.

In 2019, the second season of Star Trek: Discovery, set during Pike's tenure as captain of the Enterprise, featured Number One's first on-screen appearance in 53 years, now played by Rebecca Romijn. Romijn reprised her role in two episodes of Star Trek: Short Treks the same year, and, beginning in 2022, as a series regular in Star Trek: Strange New Worlds, which is centered on the adventures of Pike's crew.