Final answer:
Octavian was given the title Augustus by the Senate in 27 BCE, marking the beginning of the Roman Empire under his rule as the first emperor. He played a pivotal role in establishing the principate which maintained a semblance of the Republican order. Octavian, also known as Augustus Caesar after this date, was not a part of the First Triumvirate, which included Caesar, Pompey, and Crassus.
Step-by-step explanation:
The Senate honored Octavian by giving him the name Augustus in 27 BCE, which means "revered one" and is associated with gods and heroes of the past. This was to honor his service and de facto assumption of power, thus beginning the Roman Empire. His complete title became Augustus Caesar, and he is best known by this name.
After his victory over Antony and Cleopatra, he had the societal and military support necessary to consolidate power and establish the principate as a new form of government that kept the appearance of the Republic while embodying the reality of an empire with Augustus as the first emperor.
In the First Triumvirate, the members were b. Caesar, Pompey, Crassus. The Second Triumvirate included c. Marc Antony, Octavian, Lepidus.