Yuhanna ibn Masawaih, , also written Ibn Masawaih, Masawaiyh, and in Latin Janus Damascenus, or Mesue, Masuya, Mesue Major, Msuya, and Mesuë the Elder was a Persian physician, trained by Jabril ibn Bukhtishu, who was a member of the Church of the East, from the Academy of Gondishapur. According to The Canon of Medicine for Avicenna and 'Uyun al-Anba for the medieval Arab historian ibn Abi Usaybi'a, Masawaiyh's father was from Khuzestan and his mother was a Slav.