Final answer:
The end to the Roman Republic occurred when Octavian, later known as Augustus, came to power and established the Roman Empire after the fall of Julius Caesar and the defeat of Marc Antony.
Step-by-step explanation:
The end of the Roman Republic is often marked by the rise to power of Julius Caesar, who became increasingly powerful around 70 BCE. However, the true transformation and the definitive end came with Octavian (later known as Augustus), who succeeded in dismantling the Republican system and establishing the Roman Empire after defeating Marc Antony in 31 BCE. Despite the problems that plagued the Republic, such as the concentration of wealth and power among elites, the class struggles, and frequent civil wars, the end of the Republic was not an inevitability, but the result of specific actions taken by ambitious leaders like Caesar and Octavian.