Sejanus was a trusted advisor of the second Roman emperor, Tiberius.
Annotated gallery of the first 12 emperors of ancient Rome.
Augustus, a fascinating and controversial man, may have been the most important figure in Roman history. Through his long life (63 B.C. - A.D. 14) and deeds, the failing Republic was converted to a Principate that endured for centuries
Germanicus Caesar was one of the Julio-Claudians, although he didn't make it to emperor of Rome.
Poppaea Sabina - Claim to Fame: Poppaea Sabina was the mistress of one Roman emperor, Nero, at the same time she was the wife of Marcus Salvius Otho -- later to become one of the emperors in the year of the four.
The Annals, by P. Cornelius Tacitus, Book I
The primary source (from antiquity) we have for information on the Julio-Claudian emperors.
Stemmata of the Julio-Claudian emperors
The lines of consanguinity among the first five emperors are hard to keep straight. Even with this chart, it will take time to unravel the bloodline, marriage and adoption threads, but it's a useful reference tool.