First of two long-term prefects of Judea & Samaria appointed by Tiberius.  Josephus portrayed him as manipulating Jerusalem's temple politics by deposing the incumbant Sadducean high priest Hanan I (6-15 CE), as well as three short-termed successors [Ishmael ben Phiabi, Eleazer ben Hanan & Simon ben Kamith], before finally finding Joseph Kayyafa [Caiaphas], who had a long tenure collaborating with Roman military rule (18-37 CE).

References: Josephus. Antiquities 18.33-35, 177.

Other resources on line:

• Valerius Gratus - brief entry in Wikipedia's web.