Brontinus (Greek: Βροντῖνος; 6th-century BCE) or Brotinus of Metapontum, was a Pythagorean philosopher, and a friend and disciple of Pythagoras himself. Alcmaeon dedicated his works to Brontinus as well as to Leon and Bathyllus. Accounts vary as to whether he was the father or the husband of Theano.
His fame was sufficient for a spurious work to be ascribed to him in the Neopythagorean literature. Syrianus (5th century CE) refers to "Brotinus" as an author of the view that the monad, or first cause, "transcends all kinds of reason and essence in power and dignity," whereby an attempt was made to insert an element of Platonism into Pythagoreanism.
- Diogenes Laërtius, viii. 83
- Diogenes Laërtius, viii. 42; Suda, Theanô; Iamblichus, Vit. Pyth. § 267.
- Clement of Alexandria, Stromata, i. 131; Suda, Orpheus
- Kathleen Freeman, (1959), The pre-Socratic philosophers: a companion to Diels, Fragmente der Vorsokratiker, page 6.
- Syrianus, In Metaph. 166
- Philip Merlan, (1963) Monopsychism mysticism metaconsciousness: Problems of the soul in the neoaristotelian and neoplatonic tradition, page 8. Nijhoff
- Elisabeth Gellert, Jelena O. Krstovic, (2001), Classical and Medieval Literature Criticism: Excerpts from Criticism of the Works of World Authors from Classical Antiquity Through the Fourteenth Century, page 236. Gale/Cengage Learning. ISBN 0-7876-5155-9