Heinrich Alexander (from 1841 Freiherr) von Arnim(-Suckow) (born 13 February 1798 in Berlin; died 5 January 1861 in Düsseldorf) was a Prussian statesman.

Arnim received his education in the Pädagogium in Halle, then in 1814 joined the cavalry of the Landwehr of the Uckermark and fought with five brothers in the War of the Sixth Coalition.

He joined the Prussian civil service in 1820, he was at first an embassy attaché in Switzerland, then a legation secretary in Munich, Copenhagen and Naples and was made chargé d'affaires in Darmstadt in 1829.

After the end of the July Monarchy (February 1848), he hurried to Berlin and on 17 March handed the King a memorandum, in which he advocated liberal reforms and the pursuing of a German national policy.

Due to this last pamphlet Arnim was prosecuted in court at the instigation of the feudal party, and despite a stellar defence that he later published, he was convicted and sentenced to pay a fine.