Theodor Leschetizky (22 June 1830 – 14 November 1915) (Polish: Teodor Leszetycki) was a Polish pianist, professor and composer.
Theodor Leschetizky was born on the estate of the family of Count Potocki in Łańcut. His father was a gifted pianist and music teacher of Viennese birth. His mother Therèse (von) Ulmann was a gifted singer of German origin. His father gave him his first piano lessons and then took him to Vienna to study with Czerny. At age eleven, he performed a Czerny piano concerto in Lemberg (near Łańcut), with Franz Xaver Wolfgang Mozart (the son of Wolfgang Amadeus Mozart) conducting. At the age of fourteen, he started to tutor his first pupils. By the age of eighteen he was a well-known virtuoso in Vienna and beyond. His composition teacher was Simon Sechter, subsequently the teacher of Anton Bruckner, who also gave Schubert one lesson in counterpoint a few weeks before his untimely death.

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 one of the founders of the St. Petersburg Conservatory of Music in 1862. While in Russia he married one of his most famous pupils, Anna Yesipova (the second of his four wives), and had two children (one of them Robert Leschetizky).

In 1878 he returned to Vienna and began teaching there, creating one of the most eminent private piano studios in history, second only perhaps to that of Franz Liszt in Weimar. He taught thousands[citation needed] of students in the Weimarerstraße (formerly the Carl Ludwigstraße) XIX. Bezirk Wien, Vienna. They came from all over the world, many from the United States. He taught until the age of 85, leaving for Dresden in 1915, where he died that year.
He was survived by a son, Robert (Dresden), whose family returned to Bad Ischl after his death. His descendants still live in Bad Ischl and there is a Leschetizky Villa at the Leschetizky Straβe, the summer resort where he often vacationed with his friend Johannes Brahms.

Leschetizky had a granddaughter, Ilse Leschetizky (1910–1997), who was a distinguished pianist and teacher. One of her daughters, Margret Tautschnig, continues the Leschetizky tradition with the Leschetizky Verein Ősterreich in Bad Ischl. This organisation was co-founded by the Belgian pianist Peter Ritzen.
Among his celebrated Vorbereiter (assistants who prepared students to play for him) were Vorbereiterinnen Katharine Goodson, Annette Hullah, Marie Prentner and Malwine Brée, author of The Leschetizky Method (a title he approved of even though he said there "was no method!"). The list of legendary pianists he taught includes Anna Yesipova, Richard Buhlig, Ignaz Friedman, Ignacy Jan Paderewski, Artur Schnabel, Mark Hambourg, Alexander Brailowsky, Alexander Winkler, Benno Moiseiwitsch, Paul Wittgenstein, Ossip Gabrilowitsch, Elly Ney, Natalia Polnazkovski and Mieczysław Horszowski.

Perhaps the secret of his successful teaching was that he worked with each student's personality and technical abilities in an individual way. His famous weekly classes provided his students the opportunity to try out their pieces prior to public performances before a discerning audience of their fellow students and invited guests.

A humorous probable allusion to Leschetizky occurs in the "Stella in Oxford" Chapter (Book Three, Chapter 10) of Compton Mackenzie's 1913-1914 novel Sinister Street, which mentions a notable piano teacher in Vienna "with a perfectly impossible name beginning with L".

Until his death he espoused a philosophy of music-making and life, captured in one of his most famous sayings (translated from the German):

"No art without life, no life without art."
Leschetizky composed over a hundred characteristic piano pieces, two operas: Die Brüder von San Marco and Die Erste Falte, thirteen songs and a one-movement piano concerto. Opus numbers were given to 49 works.

Although his piano pieces are primarily smaller works in the salon music vein, they are expressively lyrical on the one hand while exploiting the piano's technical capabilities to great effect on the other. Most of his music has been out of print since the early twentieth century except for the Andante Finale, Op. 13 (a paraphrase for piano left hand on the famous sextet from the opera Lucia di Lammermoor by Donizetti); and Les deux alouettes, Op. 2, No. 1.