Today is the feast day of St. Catherine of Siena, a Dominican tertiary and mystic who suffered the stigmata. She died in Rome in 1380 at 33 years of age. She received celestial visions and, as did many medieval women mystics, considered herself a Bride of Christ, devoting her virginity to Him at the age of 7. She tended the sick and poor; one legend has it that she ate nothing but the consecrated Host and occasionally drank water from the bowls she used to wash the sores of lepers. She served as an ambassador for the church during the political tumult prior to the Great Schism. Her icons include the lily, the book, the crown of thorns, and the heart.
Some sources will tell you that she had a mystical vision of marrying Christ. What they often do not tell you is that in this vision, the wedding ring proffered was made of the circumcised foreskin of the Christ child.
She is invoked against fire, illness, and temptations.
Cosmas and Damian (unfortunately reproduced in many hoodoo-type places as Comas or Cosmos and Damien) were twin brothers and physicians who lived in Asia Minor in the 3rd century. They got martyred during the reign of Diocletian. Diocletian, an autocrat and anti-republican who eventually took the name Dominus et Deus (Lord and God), made a lot of martyrs. He ordered the greatest persecution of Christians in the Roman Empire that the Empire had yet seen. (This is the sweep that got St. Sebastian, one of my dear personal saints).
Cosmas and Damian are, predictably, called on for cases of illness, and as the patron saints of doctors and pharmacists.
In voodoo, they are often associated with the loa the Marassa ("Twins").
Prayer for communion, ref Ps. 78, 2. 11. "They have given the dead bodies of Thy servants to be meat for the fowls of the air: the flesh of Thy Saints for the beasts of the earth: according to the greatness of Thy arm, take possession of the children of those who have been put to death."