Saint, pope a.d. 116?–125?.
- Sixtus II
noun 1. Saint, died a.d. 258, pope 257–258.
- Sixtus III
noun 1. Saint, pope a.d. 432–440.
- Sixtus IV
noun 1. (Francesco della Rovere) 1414–84, Italian ecclesiastic: pope 1471–84. noun 1. original name Francesco della Rovere. 1414–84, Italian ecclesiastic; pope (1471–84). Notorious for his nepotism and political intrigue, he was also a patron of the arts and commissioned the building (1473–81) of the Sistine Chapel
- Sixtus V
noun 1. (Felice Peretti) 1521–90, Italian ecclesiastic: pope 1585–90. noun 1. original name Felice Peretti. 1520–90, Italian ecclesiastic; pope (1585–90). He is noted for vigorous administrative reforms that contributed to the Counter-Reformation