Possidius (died 437?) wrote the first biography of Augustine, in which he tells of their 40 years of close friendship.
He was born in Northern Africa. Little is known of his childhood and youth.
Possidius was a member of Augustine's monastic community in Hippo, along with Saint Alypius.
He was named Bishop of Calama (Numidia). There he faced opposition from the Donatists. On one occasion Donatist extremists set fire to a house where Possidius was visiting. Possidius narrowly escaped death.
Twice he went to Italy to defend his Church. He was present at the Councils of the African Church in Carthage in 403 and 407, and was chosen along with Alypius and Augustine to represent the Catholic Bishops at the famous meeting with the Donatists in Carthage in 411, where he took an active role.
Possidius was charged with official missions to Emperor Theodosius in 409 and in 410.
He took part in the Councils of Malevi (416) and Carthage (419). These Councils were in opposition to the Pelagian heresy.
When Calama was conquered by Vandal invaders in 429, Possidius took refuge with Augustine inside the walls of Hippo. Possidius was with Augustine at his death in 430.
Hippo itself was attacked and burned in 431. Possidius did return to Calama, but in 437 was exiled by King Hunmeric, who suppressed Christianity and forced Arianism on the territories that he conquered. During this time of exile, Possidius completed his famous book, The Life of Augustine. Little else is know about the activities of Possidius during this exile.
He died in exile around the year 437.