Nicomachus (Greek: Νικόμαχος; fl. c. 325 BC) was the son of Aristotle.
The Suda — a massive 10th-century Byzantine encyclopedia of the ancient Mediterranean world — states that Nicomachus was from Stageira, was a philosopher, a pupil of Theophrastus, and, according to Aristippus, his lover. He may have written a commentary on his father's lectures in physics. Nicomachus was born to the slave Herpyllis, and his father's will commended his care as a boy to several tutors, then to his adopted son, Nicanor. Historians think the Nicomachean Ethics, a compilation of Aristotle's lecture notes, was probably named after or dedicated to Aristotle's son. Several ancient authorities may have conflated Aristotle's ethical works with the commentaries that Nicomachus wrote on them. Ancient sources indicate that Nicomachus died in battle while still a "lad".
Aristotle's father was also called Nicomachus.