Aleksa Nenadović (Serbian: Алекса Ненадовић, 1749–4 February 1804) was a Serb militia commander and obor-knez (Christian mayor) of the Tamnava–Posavina knežina of the Valjevo nahiya of the Pashalik of Belgrade. A veteran of the Serbian Free Corps that fought in the Austro-Turkish War (1788–1791), he became one of the leading Serbs in the province, and was killed by the renegade Janissaries in the event known as the "Slaughter of the Knezes", which led to the First Serbian Uprising (1804–13) and Serbian Revolution.
His younger brother was Jakov Nenadović, a vojvoda (general) and the first Serbian Interior Minister. His sons were archpriest and one of the main leaders in the uprising, Matija Nenadović, and vojvoda Sima Nenadović, active in the Second Serbian Uprising (1815–17).