a reasonable selection would certainly include Marius and also include Sulla, Scipio Africanus, Fabius, Crassus, Pompey and of course, Julius Ceaser himself.
If fame is the key and not power/influence one would include Cicero, Brutus, and Cato the Censor, and possibly the Grachae.
Brutus the leader of the
Optimates in the Caesarian Civil War was descendant from Lucius Junius Brutus, considered the "founder" of the Republic for leading the revolt that ouster the Etruscan Kings. Even late in the Principate there were Emperors who refered to Brutus as the father of the Republic.
There were figures who became almost legendary in the time when Rome was but a city-state struggling against other polities in Latium, such as Marcus Furius Camillus, honored as the "Second Founder of Rome" (after Romulus). The Cornelli Scipiones - Africanus who defeated Hannibal and Asiaticus who wrecked the remaining influence of the Seleucids in Anatolia.
Other famous figures were already mentioned - Fabius Maximus (whose name led to the expression "Fabian strategy"), L. Cornelius Sulla, C. Pompeius Magnus, G. Julius Caesar... the Gracchi brothers were instrumental in the political reforms that granted a lot more status to the so-called Plebeians (which, in reality, meant the increasing influence of the Equestrian class, whose apogee came in the late stage of the Principate).
Really, what we know as "the Roman Empire" was actually built within the timespan of the Republic.