Wikipedia
Herpyllis
Herpyllis of Stagira was Aristotle's mistress after his wife, Pythias, died (Herpyllis was formerly a slave of Pythias).
Together Aristotle and Herpyllis had a son, named Nicomachus after Aristotle's father. Nicomachus was quite young when Aristotle wrote his will, as can be seen from the fact that Nicanor, Aristotle's nephew by his sister Arimneste, is appointed guardian until Nicomachus came of age.