Engelbert I of Nassau (c. 1370, in Dillenburg – 3 May 1442, in Breda) was a son of Count John I of Nassau-Siegen and Countess Margaret of the Mark, daughter of Count Adolph II of the Marck.

[1] Engelbert of Nassau was a student in Cologne, Germany in 1389 and a dean in Münster from 1399 to 1404.

Engelbert's brothers were childless and he left the deanery so he could marry Johanna van Polanen in 1403.

[3] They had six children: Engelbert had an illegitimate daughter with an unknown mistress: He died May 3, 1442, in Breda.

A mausoleum was built for Engelbert in the Church-of-Our-Lady (the Great Church) in Breda.