Landgrave Ernest of Hesse-Rheinfels-Rotenburg (8 December 1623 – 2 May 1693) was from 1649 to 1658 his death 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.