Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
I.e., as known in Roman history, Tiberius Claudius Nero, only mentioned in Lk. 3:1. He was the stepson of Augustus, whom he succeeded on the throne, A.D. 14. He was noted for his vicious and infamous life. In the fifteenth year of his reign John the Baptist entered on his public ministry, and under him also our Lord taught and suffered. He died A.D. 37. He is frequently referred to simply as "Caesar" (Mt. 22:17, 21; Mk. 12:14, 16, 17; Lk. 20:22, 24, 25, 23:2; Jn. 19:12, 15).