Demetrius III Aniketos (Greek: Δημήτριος Γ΄ ὁ Ἀνίκητος; epithet means "the Invincible") is an Indo-Greek king who reigned in the area of Gandhara and Punjab.

The two namesakes share the war-like epithet "The Invincible" and wear elephant-crowns, the symbol that Alexander the Great used to celebrate his conquest of the Indus Valley.

The absence of absolute proofs of dating Demetrius III (such as counter-marked coins), and the remaining problems of all current reconstructions, means the problem is not definitely solved, and the alternative chronology would be to place Demetrius III around 150 BCE in compliance with Tarn's and Narain's ideas about his identity as a Euthydemid prince who fought against Eucratides.

The symbols of his coin connect him with several Euthydemid kings: the kausia hat on one of his portrait with Antimachus I, the elephant-crown and the title Aniketos as mentioned with Demetrius I, and the standing Zeus on his silver reverses with Agathocles.

On his silver, Demetrius III appears in the kausia hat (on the unique known tetradrachm) or diademed, with a reverse of Zeus holding thunderbolt.