Phillipos Monotropos or Philippus Solitarius ("Phillip the Recluse"; ; 1080) was a Byzantine monk and writer, notable for his authorship of the Dioptra ("The Mirror"), written towards the end of the eleventh century.
Philip probably lived on Mount Athos. The five-volume Dioptra is a compendium of prose and verse intended to educate the next generation. In the first volume, a sinful monk repents to his soul. In the following four volumes, a dialogue continues between the body and the soul.