Countess Emilia of Nassau (10 April 1569 – 16 March 1629) was the third and youngest daughter of William the Silent and his second wife Anna of Saxony.

Due to this infidelity Emilia and her siblings, Anna and Maurice, were taken out of their mother's care and went to live with their uncle John VI, Count of Nassau-Dillenburg at Dillenburg.

It was on one of those occasions that she met Dom Manuel of Portugal, son of the Avis claimant of the Portuguese throne, António, Prior of Crato).

Maurice put Emilia under house arrest; Dom Manuel had to flee to Wesel.

When Maurice found he could not convince her to divorce her husband, he banished her from court for ten years.