The Holy Unmercenaries

The Holy Unmercenaries (Anargyri) are physicians who in their lives on earth worked to heal all without concern for gain; and who since their repose continue to heal by their prayers those who call on them in faith. They include:

Some find it implausible that there should be three distinct pairs of Anargyri named Cosmas and Damian, and conclude that there was only one such historical pair. The Synaxarion of Ormylia Monastery (Vol. 1, p. 409 note) says:
The oldest testimony to the veneration of Saints Cosmas and Damian relates to the basilica built in their honour at Cyrrhus, north of Antioch in Syria, mentioned in the Life of St Rabula of Edessa (c. 400). Their veneration spread rapidly throughout the Empire; in the East, where the famous Cosmidion was founded at Constantinople in 439, as well as in Rome and the West(see 1 July). Their widespread veneration and the dispersal of their relics are probably reasons why Cosmas and Damian came to be regarded as three distinct pairs of saints of the same names.
  None the less, the Church's Synaxaria have commemorated three different pairs of Sts Cosmas and Damian from very early times, and we continue to do so here.