Theodor Leschetizky (22 June 1830 – 14 November 1915) (sometimes spelled Leschetitzky,[1] in Polish: Teodor Leszetycki) was a Polish pianist, professor and composer born in Łańcut, then Landshut in the kingdom of Galicia and Lodomeria, also known as Austrian Poland, a crownland of the Habsburg Monarchy.
Theodor Leschetizky was born on 22 June 1830 at the estate of the family of Count Potocki in Łańcut, Poland. Joseph Leschetizky, his father, was a gifted pianist and music teacher of Viennese birth. His mother Thérèse von Ullmann was a gifted singer of German origin. His father gave him his first piano lessons and then took him to Vienna to study with Carl Czerny. At age eleven, he performed a Czerny piano concerto in Łańcut, with Franz Xaver Wolfgang Mozart, the son of Wolfgang Amadeus Mozart, conducting. At the age of fifteen he started to tutor his first students. By the age of eighteen he was a well-known virtuoso in Vienna and beyond. His composition teacher was Simon Sechter, an eminent professor who was the teacher of many other successful musicians.

At the invitation of his friend Anton Rubinstein, he went to St. Petersburg to teach in the court of the Grand Duchess Yelena Pavlovna. Remaining there from 1852 to 1877, he was head of the piano department and one of the founders of the St. Petersburg Conservatory of Music in 1862. While in Russia he married one of his most famous students, Anna Essipova, the second of his four wives, with whom he had two children; one of them was his daughter, the well-known singer and teacher, Theresa, the other was his son Robert.

In 1878 he returned to Vienna and began teaching there, creating one of the most eminent private piano schools in the world. He taught Ignacy Jan Paderewski, Artur Schnabel, Fannie Bloomfield Zeisler, Mieczysław Horszowski, Alexander Brailowsky, Benno Moiseiwitsch, Katharine Goodson, Elly Ney, Ossip Gabrilowitsch, Mark Hambourg, Isabelle Vengerova and a host of many other wonderful pianists in his villa in the Währing Cottage District on Karl-Ludwig-Straße, Vienna. Promising pianists flocked to him, coming from all over the world, with a great many from the United States, among them also classical singer Clara Clemens, the daughter of Mark Twain.

From 1904 to 1908, he was assisted by one of his students, Ethel Newcomb, an experience which proved a fertile ground for background research for her 1921 book, Leschetizky as I Knew Him.[2][3][4]

He taught until the age of 85, leaving for Dresden in 1915. He died on 14 November 1915 in Dresden.