Karl Arnold (21 March 1901 – 29 June 1958) was a German politician.
He was Minister President of North Rhine-Westphalia from 1947 to 1956.
From 7 September 1949 until 8 September 1950 he was President of the German Bundesrat.
He is, together with Jens Böhrnsen (in 2010) and Horst Seehofer (in 2012), one of the three Presidents of the Bundesrat who have acted as head of state during a vacancy of the office of President, according to Article 57 of the Basic Law.