The Sonata No. 16 in C major, K. 545, is a piece of music for solo piano. It was composed by Wolfgang Amadeus Mozart. On 26 June 1788, he added the piece to his catalogue as "a little Piano Sonata for beginners". He may have written the piece for a pupil. If he did, that pupil is not known. In the end, the story behind the sonata is a mystery.