Arnold of Altena, count of Altena, count of Isenberg and Hövel, Vogt of Werden (1166–1209) was a son of Eberhard IV of Berg. He inherited the north-western territorium of Altena, and became 1st count of Isenberg in 1200. He married Mathilde countess of Cleve daughter of Dietrich III, Count of Cleves and Adelaide of Sulzbach (+12.2.1189). Mathilde's brother was count Diederick IV of Cleve (+1193) who married in 1182 Mechteld (Margaret) of Holland (died after 1203).
Count Arnold of Altena – Isenberg and Mathilde countess of Cleve had issue:
- Eberhard II count of Altena and Isenberg (born 1180, died 1209)
- Friedrich II of Isenberg, count of Altena and Limburg-Isenberg (beheaded at Cologne 13 November 1226);
- Dietrich of Altena, (born before 1180, died on the way back from Rome to Limburg 18 July 1226);
- Engelbert of Altena, (1224-deposed 1226 following his implication in Engelbert II of Berg's assassination, rehabilitated 1238-1250) (born before 1200, died 1250);
- Philipp of Altena, Propst zu Soest and Domthesaurar in Cologne (born before 1200, died 1264);
- Bruno of Altena, (1250–1258) (born before 1200, died 20 December 1258);
- Gottfried of Altena, Propst zu St. Martin and Domdechant in Münster (born before 1220, died after 1247);
- Adolf von Holte (born 1220, died before 25 January 1260), married to Elisabeth von Holte (died after 1260). They had issue:
- Heinrich von Holte, a prior in Cologne (fl. 1261/89);
- Arnold von Holte, a priest (fl. 1266);
- Wilhelm von Holte, a priest (fl. 1281);
- Mechtild von Holte, heiress of Holte and Morenhoven (died 1301), married to Gerhard von Arberg, Bggf von Köln (died 1287);
- Heilwig (fl. 1237/46), married to Wilhelm I von Horn; and
- Christina (fl. 1257), married to Albero Schalle;
- Wilhelm of Altena, also called Wilhelm of Isenberg (1223-1242). He had a son, Wilhelm (fl. 1275), married to Christina NN;
- NN, a daughter, married to Hermann of Altena.
- Agnes of Altena, a daughter, married to Christian II, Count of Oldenburg.