This article does not cite any references or sources. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2006)

Nicomedes III Euergetes (Ancient Greek: Νικομήδης Εὐεργέτης, Nikomḗdēs Euergétēs) was the king of Bithynia, from c. 127 BC to c. 94 BC. He was the son and successor of Nicomedes II.

He made himself for a time master of Paphlagonia, and in order to have a claim on Cappadocia married Laodice (the widow of Ariarathes VI), who had fled to him when Mithradates the Great endeavoured to annex the country.

When her two sons – Ariarathes VII and Ariarathes VIII – died, Nicomedes brought forward an impostor as a claimant to the throne; but the plot was detected. The Romans refused to recognize the claim, and required Nicomedes to give up all pretensions to Cappadocia and to abandon Paphlagonia.

This may be the Nicomedes referred to in 'Fortune's Favourite', & 'Caesar' (Rome series, author Colleen McCullough), see her bibliography for sources.