Seuthes II (Ancient Greek: Σεύθης) was a king of the Odrysian kingdom of Thrace from about 405 to 391 BC. His rule was contemporary with that of Amadocus I, who at the beginning of his own reign made him ruler of the kingdom's Aegean shore territory. Later Seuthes apparently revolted; Aristotle mentions a King Amadocus who was attacked by his general Seuthes, probably in reference to these individuals. Seuthes proclaimed himself king at the end of the 5th century. According to Xenophon, who was in the country in the winter of 400-399 BC, Seuthes and Amadocus were then powerful rival rulers who faced off frequently. They were ultimately reconciled with each other and made allies of Athens by the Athenian general Thrasybulus in 390 BC.
He married Stratonice of Macedon, the sister of Perdiccas II of Macedon.