lay figure

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. See mannequin.
2. n. A subservient or insignificant person.

Century Dictionary and Cyclopedia

1. n. A jointed figure used by painters, made of wood, cork, etc., in imitation of the human body. It can be placed in any position or attitude, and serves when clothed as a model for draperies, etc. Formerly also called layman.
2. n. Hence A living person or a character in fiction who lacks individuality, or who is treated merely as a foil or puppet.

Wiktionary

1. n. A jointed model of the human body used by artists, or to display clothes.
2. n. An unimportant person.

GNU Webster's 1913

1. n. A mere puppet; one who serves the will of others without independent volition.

WordNet 3.0

1. n. dummy in the form of artist's jointed model of the human body