Chandragupta Maurya (340-298 B.C.) was the first ruler of the empire that bore his name. He is credited with unifying the Indian state, a feat considered all the more remarkable for the previous failure of Alexander the Great to accomplish much the same goal, albeit for vastly different reasons (Alexander sought to expand the Macedonian empire, but failed to advance past current-day Pakistan, still considered part of the Indian subcontinent). Chandragupta's period of rule extended from 322 B.C. until he stepped down in favor of his son soon before his death. One of Chandragupta's greatest obstacles was the power of the Nanda Empire, which encompassed a large expanse of central and eastern India, and which had accumulated enormous wealth during its reign (345-321 B.C.). According to historians, what Chandragupta's army lacked in size, especially relative to the formidable military maintained by the wealthy Nanda rulers, it made up for with tactical genius, enabling it to overcome its disadvantage in numbers.
In short, then, Chandragupta Maurya was the leader of the first ruler of the Maurya Empire, which is credited with unifying the Indian subcontinent.