1530s, "image of a person," from Middle French effigie (13c.), from Latin effigies "copy or imitation of something, likeness," from or related to effingere "mold, fashion, portray," from ex- "out" (see ex-) + fingere "to form, shape" (see fiction). The Latin word was regarded as plural and the -s was lopped off by 18c. Specifically associated with burning, hanging, etc., at least since 1670s.
Symbolically. For example, That umpire was completely unfair—let's burn him in effigy. Now used only figuratively, this term formerly signified a way of carrying out the sentence of a criminal who had escaped, such as burn in effigy or hang in effigy. A dummy was made of the criminal or a detested political figure and subjected to the prescribed punishment. [c. 1600]