Ludwig van Beethoven's Piano Sonata No. 27 in E minor, Op. 90 was written in the summer of 1814 – Beethoven's late Middle period – and dedicated to Prince Moritz von Lichnowsky, a friend and benefactor who was also the dedicatee of the Eroica Variations.

Ludwig van Beethoven was a German composer and pianist. He is one of the most revered figures in the history of Western music; his works rank among the most performed of the classical music repertoire and span the transition from the Classical period to the Romantic era in classical music. His early period, during which he forged his craft, is typically considered to have lasted until 1802. From 1802 to around 1812, his middle period showed an individual development from the styles of Joseph Haydn and Wolfgang Amadeus Mozart, and is sometimes characterized as heroic. During this time, Beethoven began to grow increasingly deaf. In his late period, from 1812 to 1827, he extended his innovations in musical form and expression.