Brontinus was a philosopher from the Greek colony of Metapontum in southern Italy, active in the sixth century BCE. He is known as an early member of the Pythagorean school, a community founded by Pythagoras that focused on mathematics, philosophy, and a disciplined way of life. Ancient sources place him at the heart of this group, suggesting he was either the father or the husband of Theano, a figure closely associated with Pythagoras. Beyond this connection, few details of his life are known.

No writings definitively by Brontinus survive. Later ancient authors attributed a few works to him, such as a text On Intellect and Discipline and some poems concerning mystic rites. According to modern scholars, these attributions are almost certainly not genuine. They are considered later pseudepigrapha—writings composed in a later period and assigned to an early, authoritative name like Brontinus to lend them credibility.

His historical importance lies primarily in his early association with Pythagoras and his community. He represents the inner circle of disciples in the founding period of Pythagoreanism in Italy. While the historical Brontinus was likely a respected figure, his name later became a vessel for anonymous philosophical and religious poems, illustrating how early Pythagorean figures were used to legitimize later ideas.