Tiberius (thanks to Justin Paola)
May 2016 - Tiberius was Augustus' step-son - he was the son of Augustus' wife Livia, from Livia's first marriage. He was born in 42 BC. Tiberius' father was also called Tiberius - his name was Tiberius Nero, and he was from the Claudian family - a very rich and powerful family. When Tiberius was only three years old, his mother, Livia, divorced Tiberius Nero and married Octavian, who would later become the emperor Augustus.
Tiberius' real father, Tiberius Nero, died when Tiberius was nine years old. Tiberius was the one who gave a speech at his father's funeral, even though he was still a kid. When Tiberius grew up, his step-father Augustus sent him on various missions to give him experience in government, so that one day he could rule the Roman Empire. For instance, Tiberius went with his brother, Nero Claudius Drusus, to fight against the Germans in the Alps, north of Italy.
Tiberius also got married about this time (about 20 BC, when he was 22) to Vipsania Agrippina, who was the daughter of Augustus' favorite general, Agrippa. In 13 BC, Vipsania and Tiberius had a baby son, who they named Julius Caesar Drusus. But after this happy time, Tiberius' life got harder. When Agrippa died in 12 BC, Augustus forced Tiberius (who was now 30 years old) to divorce Vipsania and marry Agrippa's widow (Vipsania's stepmother), Julia Caesaris, even though Tiberius really didn't want to. They never had any children. Augustus wouldn't even let Tiberius see Vipsania anymore. A little later, in 9 BC, Tiberius' brother Drusus died unexpectedly.
As his reward for obeying everything Augustus ordered him to do, though, Tiberius got closer and closer to being the next emperor. He did more fighting in the army, and he won a bunch of battles. But he was very unhappy, and in 6 BC, when Tiberius was 36 years old, he quit all his army positions and everything else and announced that he was moving to the island of Rhodes (far away in the Aegean Sea) and would not participate in politics any more, ever.
Augustus was upset when Tiberius moved to Rhodes, because he had no other sons to succeed him (he had a daughter, Julia, but Augustus didn't think girls could have power). Augustus wouldn't let Tiberius come back to Rome for visits to his mother, Livia, and (according to Tacitus) Tiberius thought that any day Augustus might send soldiers to Rhodes to kill him.
In the end, though, Augustus didn't have anybody else to succeed him when he died, and he was forced to let Tiberius come back to Rome and make him his heir, and Tiberius was more or less forced to agree to be the next emperor. Augustus also made Tiberius adopt his nephew Germanicus (his brother Drusus' son) as his own heir, even though Tiberius already had a son, Drusus. When Augustus died in 14 AD, the Senate voted to make Tiberius, who was already 55 years old, the next emperor. Tiberius protested that he was too old, and didn't really want to be emperor, but historians aren't sure whether he was serious. Anyway, he became the emperor.
At first, Tiberius favored his adopted son (his nephew) Germanicus, as Augustus had wanted, and certainly Germanicus was very popular with everyone, much more popular than Tiberius' own son, Drusus. But Germanicus died while he was fighting in West Asia in 19 AD, and as he was dying, he accused Tiberius' friend Piso of killing him. People thought that if Piso had killed Germanicus, it must have been because Tiberius told him to. Nobody knows what the truth is. Piso killed himself while he was on trial, and Tiberius never commented at all.
But after Germanicus and Piso died, Tiberius was less and less willing to be emperor. He started letting the head of the palace guards, Sejanus, run things most of the time. Sejanus (sa-JANE-us) convinced Tiberius (who was now in his sixties) that everyone hated him and was trying to kill him, and only Sejanus could protect him. Tiberius believed Sejanus, and executed a lot of people for treason just because Sejanus told him to. Finally, in 23 AD, Sejanus had Tiberius' son Drusus poisoned, and he died (but Tiberius didn't realize that Sejanus was behind it). Sejanus was trying to get to be the next emperor himself.
Just as it looked like Sejanus was really going to be the next emperor, however, Tiberius suddenly had him killed. Nobody is sure exactly why, but maybe Tiberius finally realized that Sejanus was tricking him, and that he had killed Drusus. From this point on, Tiberius stopped caring about running the empire. He was 73 years old, his son was dead, and his friend had betrayed him. He spent most of his time by himself on the island of Capri in southern Italy, swimming and reading and listening to music. He wouldn't even say who should be emperor after him.
It was about this time that the Romans crucified Jesus in Jerusalem, but it's hard to imagine Tiberius was paying any attention. Tiberius died in 37 AD, when he was 78 years old. His will left the empire to his grand-nephew Caligula and his grandson Tiberius Gemellus.
Classical Rome, by John Clare (1993). For kids, the whole political history from beginning to end.
Oxford First Ancient History, by Roy Burrell (reissued 1997). Easy reading. It skips around a lot, not trying to tell everything, just highlights.
The Romans: From Village to Empire, by Mary Boatwright, Daniel Gargola, and Richard Talbert (2004). Okay, it's a little dry, but it is up to date and has all the facts you could want.
The Roman Revolution, by Ronald Syme (1960). Still a classic.
the Gracchi to Nero: A History of Rome from 133 B.C. to A.D. 68
by H. H. Scullard (1959, 5th edition 1990). Another classic.