Theophanes Chrysobalantes (, ), erroneously known as Theophanes Nonnus or Nonnos in older scholarship, was a Byzantine physician who wrote an outline of medicine dedicated to Emperor Constantine VII Porphyrogennetos.
The extant manuscripts identify the author as Theophanes; the name Nonnus was apparently fabricated by the 16th-century copyist Andreas Darmarios. The name Chrysobalantes was either an epithet or a variant of the documented Byzantine family name Chrysobalantites. Some copies of the manuscripts are anonymous or identify the author incorrectly as Michael Psellos.
Theophanes was likely a physician himself. Two works reference him as their author:
In addition, an anonymous outline on medical cures (, ) is likely part of his work, on account of similarities in the preface with those of the other two works, as well as the thematical coherence the whole represents.