Caesar (Caligula) was a Roman Emperor who reigned from 37 to 41 AD. His birth name was Gaius Julius Caesar Germanicus, but he is commonly known as Caligula. He was the third emperor of the Julio-Claudian dynasty and his full name was Gaius Julius Caesar Augustus Germanicus. His nickname, Caligula, was derived from the Latin word for 'little boot, ' which was a reference to the military boots he wore as a child. His other name, Caius, was a variant of Gaius.