Obviously, since he was the greatest general ever and super-fabulously wonderful (in my humble opinion), the treatise mentions Gaius Marius.
De Re Militari III, 10 [note that Africanus is Scipio Aemelianus Africanus]:
In former ages the art of war, often neglected and forgotten, was as often recovered from books and reestablished by the authority and attention of our generals. Our armies in Spain, when Scipio Africanus took the command, were in bad order and had often been beaten under preceding generals. He soon reformed them by severe discipline and obliged them to undergo the greatest fatigue in the different military works, reproaching them that since they would not wet their hands with the blood of their enemies, they should soil them with the mud of the trenches. In short, with these very troops he afterwards took the city of Numantia and burned it to the ground with such destruction of its inhabitants that not one escaped. In Africa an army, which under the command of Albinus had been forced to pass under the yoke, was by Metellus brought into such order and discipline, by forming it on the ancient model, that they afterwards vanquished those very enemies who had subjected them to that ignominious treatment. The Cimbri defeated the legions of Caepio, Manilus and Silanus in Gaul, but Marius collected their shattered remnants and disciplined them so effectually that he destroyed an innumerable multitude of the Cimbri, Teutones and Ambrones in one general engagement. Nevertheless it is easier to form young soldiers and inspire them with proper notions of honor than to reanimate troops who have been once disheartened.
Many of the tactics that made Marius a great general were learnt from Scipio Aemilianus, and these reforms were still appreciated into the Byzantine period.
BMCR has a review of a new book on the treatise:
Michael B. Charles, Vegetius in Context: Establishing the Date of the Epitoma Rei Militaris. Stuttgart, 2007.