The Nuttall Encyclopedia
A Greek rhetorician who flourished in the 3rd century B.C.; was distinguished for the bitterness with which he criticised Homer, and whose name has in consequence become a synonym for a malignant critic, hence the saying, "Every great poet has his Zoilus."
Wood, James, ed. Entry for 'Zoilus'. The Nuttall Encyclopedia. https://www.studylight.org/encyclopedias/eng/nut/z/zoilus.html. Frederick Warne & Co Ltd. London. 1900.