Unico Wilhelm, Count van Wassenaer Obdam (30 October 1692 – 9 November 1766) was a Dutch nobleman who was a diplomat as well as a composer.

His most important surviving compositions are the Concerti Armonici, which until 1980 had been misattributed to the Italian composer Giovanni Battista Pergolesi (1710–1736) and to Carlo Ricciotti (1681–1756).

His grandfather, Jacob van Wassenaer Obdam, was supreme commander of the confederate Dutch navy, and was killed in battle in 1665 in the Second Anglo-Dutch War; his father, Jacob van Wassenaer Obdam (younger), served as a general of the army in the War of the Spanish Succession, but ruined his military reputation in 1703 in the Battle of Ekeren, and spent the rest of his career as a diplomat.

[citation needed] Unico Wilhelm had inherited the estate of Twickel from his father in 1714 and three years later was admitted as a knight of Overijssel.

His older brother Johan Hendrik found him a position as water manager of the Rhineland (1723), counsel to the Admiralty (1724) and governor of the Dutch East India Company (1734).

Unico Wilhelm continued to spend part of his time at Twickel, and in 1726 he had maps made of this property and the rest of his inheritance.

The Concerti armonici, published anonymously in 1740, were printed in London in 1755 as compositions by the violinist and impresario Carlo Ricciotti (c. 1681–1756).

Although the handwriting was not by Van Wassenaer, the manuscript did have an introduction in his hand, reading: "Partition de mes concerts gravez par le Sr. Ricciotti".

Because of the research done by the Dutch musicologist Albert Dunning, there can be no doubt that the concerti were, in fact, written by Van Wassenaer.

Upon my refusal he enlisted the aid of Mr Bentinck, to whose strong representations I finally acquiesced, on condition that my name did not appear anywhere on the copy and that he put his name to it, as he did.

Had they not been published, I would perhaps have corrected the mistakes in them, but other business has left me no leisure to amuse myself with them, and I would have caused their editor offence."