Landgrave Ernest of Hesse-Rheinfels-Rotenburg was from 1649 to 1658 Landgrave of Hesse-Rheinfels and from 1658 until his death Landgrave of Hesse-Rheinfels-Rotenburg. Because his brothers died young, all later Landgraves in the Rotenburg Quarter are descendants of Ernest. Hence, Ernest is known as the ancestor of the Catholic Rotenburg Quarter, a group of junior lines of the House of Hesse.

Hesse-Rotenburg is a former German landgraviate created from the landgraviate of Hesse-Cassel in 1627. Its independence ended in 1834 when the estates not bequeathed to princes Victor and Chlodwig of Hohenlohe-Waldenburg-Schillingsfürst were reunited with Hesse-Kassel.