pseudepigraphy

pseudepigraphy \soo-duh-PIG-ruh-fee\, noun:

The false ascription of a piece of writing to an author.

But the apocalyptic seers were usually not content with mere anonymity; they generally practiced pseudepigraphy.
-- Shaye J. D. Cohen, From the Maccabees to the Mishnah

Even this gimmick exactly parallels the ancient scriptural practice of pseudepigraphy whereby a later, undistinguished writer, would hide behind the name of a greater figure of the past, claiming venerable authority for his own innovations.
-- R. M. Price, C. A. Smith, The Book of Eibon

Pseudopigraphy was first used in the 1830s, but a related word pseudepigrapha dates back to the 1600s. In Greek, the word epigraph meant "title, ascription to an author." With the prefix pseud, it literally means "false ascription to an author."