Achaemenēs (English pronunciation: /əˈkɛməniːz/, from Ancient Greek: Ἀχαιμένης, Old Persian: 𐏃𐎧𐎠𐎶𐎴𐎡𐏁 Haxāmaniš) was the eponymous ancestor of the Achaemenid Dynasty, who ruled Persia between 705 BC and 675 BC.

The name is a bahuvrihi compound literally translating to "having a friend's mind", or "characterized by a follower's spirit".

As the eponymous ancestor of the clan, Achaemenes is very often held to be legendary. Achaemenes is generally known as the leader of one of the clans, known to the Greeks as the Pasargadae (although this identification may been due to a confusion with the Persian Imperial capital city Pasargadae begun by Cyrus the Great {Cyrus II of Persia} around 546 BC), that was one of the some ten to fifteen Persian tribes. Persian royal inscriptions such as the Behistun Inscription place him five generations before Darius the Great. Therefore, according to the Inscriptions, Achaemenes may have lived around 700 BC. The inscriptions do label him as a "king", which may mean that he was the first official king of the Persians.