Who is Ezra ?

The priest and scribe Ezra, living in Persia, was entrusted around 459 BCE with the mission of resettling the exiled Jews in their homeland and restoring the Temple of Jerusalem.
For the theologian Hugh of Saint-Victor (1096–1141), Ezra was the scribe who transcribed the Scriptures and divided the Old Testament into 22 books. The writings bearing his name, the Book of Ezra, is the 21st.

The Old Testament, or the Hebrew Bible, is the term used by Christians for the biblical texts they share with Judaism.