What was Noah’s wife’s name? Cain and Abel’s sisters? The sisters / cousins of Jesus? The bible doesn’t tell us, but traditions and later works suggest names for the biblical nameless.
Some, like Noah’s wife, are named in classical midrashes (Naamah); others come from medieval hagiographies or Eastern Orthodox traditions, like Luluwa, the twin sister of Cain and wife of Abel.
Pretty much every unnamed character connected to Jesus has been named somewhere. Some have general agreement (Longinus, the soldier who stabbed him in the side on the cross with a spear), others have multiple options. The wise men / Magi, for example, are variously named as
- Balthasar, Melqon, Gaspar
- Balthasar, Melchior, Caspar
- Basanater, Hor, Karsudan
- Larvandad, Hormisdas, Gushnasaph
- Manatho, Alchor, Gaspar
These all presume the tradition of there being three wise men; of course that number is not specified anywhere in the Bible itself.
The Generalist Academy 
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For some reason, this makes me think of Thomas Browne’s Hydriotaphia, “What song the Syrens sang, or what name Achilles assumed when he hid himself among women, though puzzling questions, are not beyond all conjecture.”