Hail Mary
Before the 16th century, the Hail Mary greeted and praised Mary.  However, during the 16th century, new words were added.  These new words asked Mary for help.  In 1555, a Dutch Jesuit named Petrus Canisius added these words to his catechism: "Holy Mary, Mother of God, pray for us sinners."  By the time of the Council of Trent eleven years later, this sentence, and some new words, had been added to the Hail Mary.  In 1566, the Catechism of the Council of Trent included this sentence in the prayer: "Holy Mary, Mother of God, pray for us sinners now and at the hour of our death. Amen."