Julii Caesares
Julii Caesares is a subdivision of the patrician Julii family in the Roman Republic, and the beginnings of the Julian side of the Julio-Claudian Dynasty. All its members had the nomen Julius and the cognomen Caesar. When further historical details are lacking they can be told apart by (often recurring) praenomina, the offices they held, the era they lived in and/or known or surmised relatives.
Descendancy
The first Caesar may have been a grandson of the Lucius Julius Libo who was consul in 267 BC. His praenomen may have been Numerius or Sextus. Genealogies show a lot of variation up to the grandfather of Julius Caesar, the Roman dictator. For these earlier generations of Caesars descendancy is largely a conjectural construct by later historians, often intended to illustrate some noble or even divine descent (e.g. translatio imperii) with little or no evidence from the period these people actually lived. From the generation of the dictator's grandfather the descendance is better documented, including the adoptions from Julius Caesar's posthumous adoption of his grandnephew Octavian.