best girl

noun3

1. •
   (Internet, slang) A reader or viewer's preferred female character.

   • Also: Miku is best girl, thank you for attending this TED Talk. — 2020
2. •
   (old-fashioned) One's girlfriend.

   • […] your fine magazine […] is a pleasure to read anywhere, but in an isolated spot such as this it's almost as good as a sugar report from the best girl! — 1954
3. •
   A woman who performs the duties of a best boy.