The Piano Concerto No. 24 in C minor, K. 491, is a concerto composed by Wolfgang Amadeus Mozart for keyboard and orchestra. Mozart composed the concerto in the winter of 1785–1786, finishing it on 24 March 1786, three weeks after completing his Piano Concerto No. 23 in A major. As he intended to perform the work himself, Mozart did not write out the soloist's part in full. The premiere was in early April 1786 at the Burgtheater in Vienna. Chronologically, the work is the twentieth of Mozart's 23 original piano concertos.

The Köchel catalogue is a chronological catalogue of compositions by Wolfgang Amadeus Mozart, originally created by Ludwig Ritter von Köchel, in which the entries are abbreviated K. or KV. Its numbers reflect the ongoing task of compiling the chronology of Mozart's works, and provide a shorthand reference to the compositions.