Boyd’s Bible Dictionary:
Tiberius Claudius Nero, second emperor of Rome, A
D. 14-37. Stepson of Augustus, a vigorous warrior, eloquent orator, and able statesman, but an indolent, despotic ruler. He is the Caesar of Luke 3:1; 20:22-25; 23:2; John 19:12.
Concise Bible Dictionary:
Bust of Tiberius Caesar, Age 46.
Son of Tiberius Claudius Nero and Livia, his name in full being the same as his father’s. He was step-son of Augustus, and was the second emperor of Rome. There is only an incidental reference to him under this name in the New Testament—the fifteenth year of his reign being the time when John the Baptist began his ministry (Luke 3:1). His reign is put down as A.D. 14-37, but there is evidence that he reigned two or three years with Augustus, and the above “fifteenth year” is reckoned from the earlier date. By comparing this with verses Luke 3:22-23, it will be seen that it could not have been later than A.D. 25 or 26; for Christ was born four years before the Era A.D., and now He “began to be about 30 years old.” Tiberius was a most profligate man, and his government was despotic and cruel.