00125-323458 was the identification number of a woman who died at the age 75 on Gliese 581d.
She was the first human to die in the colony. After her death, the whole colony was struck by grief, and the Vardy identified grief as a disease. (TV: Smile [+]Frank Cottrell-Boyce, Doctor Who series 10 (BBC One, 2017).)
Behind the scenes[]
The woman's name was never given on screen, but her personal identification number was shown.