Sure, there were lots of rebels in ancient Rome (Spartacus, anyone?), but the most fascinating people the Romans fought were leaders of rival foreign nations. These weren't just ancient Roman rebels, but monarchs, chieftains, and genius generals in their own right.
The Senate might have thought of some of these rulers as ancient Romans who rebelled, but the truth, more often than not, was that these individuals fought to achieve or keep their people independent from Roman conquest. Take, for example, Boudica, the famed British queen who slaughtered invading Romans and destroyed London.
And then there were Rome's rivals for control of trade, like Carthage. You might know Hannibal as a cannibal, but before he was a Lecter, he was a genius general who brought a ton of elephants into Italy to slaughter Romans. Hardly rebels from ancient Rome, but a kick-ass ruler in his own right.