Ignace Joseph Pleyel (18 June 1757, Ruppersthal, Lower Austria — 14 November 1831, Paris, France) was an Austrian-born French composer, piano manufacturer, music publisher, and founder of the renowned "Pleyel et Cie" company.

Ignaz grew up in Austria and likely studied with Johann Baptist Vanhal in his early years. In 1722, Pleyel became Joseph Haydn's student in Eisenstadt and subsequently established a close personal friendship as one of his favorite ex-pupils. He debuted as a composer in 1782 with Opus 1, a collection of six string quartets dedicated to his patron, Count Ladislaus Erdődy (1746—1786), who financed Pleyel's education (and admired by Mozart, as evidenced by his April 1784 letter to his father, Leopold). Pleyel soon traveled to Italy, where Ignaz wrote his first opera, "Ifigenia in Aulide" (1785), and several works commissioned by the King of Two Sicilies, Ferdinand I (1751—1825).

In 1783, Ignaz Pleyel relocated to France, taking the position of organist and assistant "maître de chapelle" (kapellmeister) under Franz Xaver Richter (1709—1789) at renowned Cathédrale de Strasbourg. It was a lucrative tenure, giving him access to a full orchestra with a choir and a generous concert budget. Ignace wrote extensively in the following decade and regularly presented new works at the Cathedral, including liturgical music and many "symphonies concertantes." After F.X. Richter died in 1789, Pleyel became the full kapellmeister but didn't last long in his new role, as the French Revolution put to end any church performances and music concerts. Ignace Pleyel went to England on the invitation by Wilhelm Cramer and led the "Professional Concerts" subscription series at Hanover Square Rooms in London — just like his teacher, Haydn, who also performed in London around the same time booked by Johann Peter Salomon. They both made a fortune on British tours, and Ignace Pleyel bought a large Château d'Ittenwiller mansion in Bas-Rhin prefecture after returning to Strasbourg.

In 1793, as political upheaval worsened in France and the "Reign of Terror" began, the infamous Committee of Public Safety summoned Ignace Pleyel, brandishing him as a "Royalist sympathizer." He narrowly escaped potential imprisonment, if not execution, by blatant collaborationist tactics, offering to "repent" his supposed misdeeds by writing several hymns and instrumental works hailing the young First Republic. Two years later, Ignace Pleyel relocated to Paris, where he established the Maison Pleyel publishing house in 1797. This new venture was successful, producing a complete edition of Haydn's string quartets in 1801 and publishing almost 4,000 works in the following forty years by Ludwig van Beethoven, Wolfgang Amadeus Mozart, Luigi Boccherini, Muzio Clementi, Johann Baptist Cramer, , , Johann Nepomuk Hummel, and George Onslow.

In 1807, fifty-year-old Ignace embraced a new profession and decided to manufacture pianos, establishing Pleyel et Cie ("Pleyel and Co.") firm. His venture soon proliferated, thanks to pioneering technological advancements, such as introducing the metal frame for grand pianos. In 1815, his son Camille Pleyel (1788—1855) joined the company as a business partner. They introduced a highly successful pianino model — a short, vertically-strung "cottage" upright piano based on the design of British maker Robert Wornum (1780—1852). Camille took over the family business after Ignace retired in 1824.

Pleyel was a prolific composer and wrote 42 symphonies, over 85 quartets, and a few operas before focusing solely on his piano company in later years. Despite an overwhelming popularity and success in his lifetime, Ignace Pleyel's music became largely obscure in subsequent years (similar to Luigi Cherubini, Giacomo Meyerbeer, Sigismond Thalberg, and a few other Classical and early-Romantic era composers). The interest in his catalog gradually increased since the 1950s; a German label Ars Produktion launched a comprehensive series of Ignaz Pleyel's recordings in 2010, now featuring over 15 albums on CD and SACD by Ignaz Pleyel Quintett, Ignaz Pleyel Quartett, IgnazJosephPleyel Orchester, and several established European chamber ensembles. The lasting impact that Ignaz Pleyel and his piano company had on the classical music world is reflected by an abundance of various groups named in his honor, from Quatuor Pleyel and Pleyel Quartett Köln to The Pleyel Ensemble and Duo Pleyel.