lay figure

noun2

1. •
   A jointed model of the human body used by artists, or to display clothes.

   • ‘I have a great mind to break all your gashly images about the head of your fine Miss, in her silks and satins;’—mistaking his lay-figure for a living model of the highest sort. — 1828
2. •
   An unimportant person; a character (especially in fiction) who lacks individuality and is one-dimensional.