Cosmas of Prague (c. 1045 – October 21, 1125) is a priest, writer and historian born in a noble family in Bohemia.

Between 1075 and 1081, he studies in Liège.

After his return to Bohemia, he becomes a priest and marries Božetěcha, with whom he probably has a son.

In 1086, Cosmas is appointed prebendary (canonicus) of Prague, a prestigious position.

As prebendary, he also travels through Europe on official matters.