Otto II of Nassau-Siegen

Otto II (c. 1305–1350/51) succeeded his father Henry I as Count of Nassau-Siegen in 1343. The 1341 partition gave him the Siegerland and Dillenburg with the surrounding lands. His reign was spent in feuds and debt: he sold or pledged lands including Löhnberg, his half of Siegen and Haiger, and won Dillenburg its city rights from Emperor Louis the Bavarian.

He was killed in his feud with the Walderdorff brothers between late 1350 and early 1351. His son John I succeeded under the regency of his widow, Adelaide of Vianden.