Pope St. Callistus I, martyr, d. about 223. Also known as Callixtus or Calixtus.

Hagiography of Pope St. Callistus I, by Terry Matz.

Biographical portrait of Pope St. Callistus I.

St. Calixtus, or Callistus, Pope, Martyr. From Fr. Alban Butler's Lives of the Saints.

Profile of Pope St. Callistus I. With links.

St. Calixtus I is known mostly through the writings of his enemies.

Short biography of Pope St. Calixtus I, by Karen Rae Keck. It was Calixtus who excommunicated Sabellius.

The story of Pope St. Callistus I, suited to children.