Composers (and musicians) have always been a good source material for movies, so there are several (by no means a complete list).
Henry Purcell:
“England, my England” (1995)
https://www.cduniverse.com/productinfo.asp?pid=7437513 J. S. Bach:“Chronik der Anna Magdalena Bach” (1968) - A little known and very interesting German biopic of Bach. All the parts are played by famous Bach interpreters (Gustav Leonhardt plays Bach and Bob van Asperen is in it too).
https://us.imdb.com/title/tt0062804/“Jagged Harmonies - Bach vs. Frederick II (Mein Name ist Bach, 2003).” - Much more passionate is Swiss director Dominique de Rivaz´s take on the meeting of Bach and Friedrich the Great (which resulted in the “Musical Offering”).
https://www.german-cinema.de/app/filmarchive/film_view.php?film_id=1017 G. F. Handel:“The great Mr. Handel” (1942)
https://www.amazon.com/The-Great-Mr-Handel/dp/B0002SQ072“Farinelli” (1994) – Although primarily a biopic of Farinelli – the castrato singer who ended up as musical director of the Spanish court at the time when Domenico Scarlatti was the Queen´s music teacher – Handel features as a major character (Sadly Scarlatti is not even mentioned...)
https://www.imdb.com/title/tt0109771/“Handel´s Last Chance” (1996)
https://movies.yahoo.com/movie/1800398158/infoW. A. Mozart: “Mozart” (1955)
https://www.mountainx.com/movies/review/mozart.php“Mozart: A childhood chronicle” (1974) – Highly recommended.
https://www.imdb.com/title/tt0071865/“Amadeus” (1984)
https://www.fast-rewind.com/amadeus.htm“Mozart: Decoded” (2008) TV documentary.
https://www.sullivanmovies.com/on_tv/onTV_details.php?library_id=92“In search of Mozart” (2007)
https://www.calendarlive.com/movies/reviews/cl-et-mozart18may18,0,4296770.storyOther movies about Mozart here:
https://home.earthlink.net/~beachwoodprs/html/MOZART.htmLudwig van Beethoven:“Immortal Beloved” (1994) – Gary Oldman as Beethoven, and all agree that the theory of the movie is spurious.
https://www.lvbeethoven.com/Fictions/FictionFilmsImmortalBeloved.htmlAbel Gance´s “Un grand amour de Beethoven” (1936).
https://www.lvbeethoven.com/Fictions/FictionFilmsGrandAmourBeethoven.html“Le Neveu de Beethoven” (1985) Beethoven as seen by his nephew Karl.
https://www.lvbeethoven.com/Fictions/FictionFilmsNeveuBeethoven.html“Eroica” (2003) TV documentary
https://www.lvbeethoven.com/Fictions/FictionFilmsEroica.html“Beethoven lives upstairs”
https://www.lvbeethoven.com/Fictions/FictionFilmsBeethovenLivesUpstairs.html“An immortal spirit”
https://www.lvbeethoven.com/Fictions/FictionFilmsImmortalSpirit.html“Copying Beethoven” (2006).
https://www.imdb.com/title/tt0424908/ Franz Schubert “In paradise with Franz Schubert” (2002)
https://www.rottentomatoes.com/m/in_paradise_with_franz_schubert/“The double life of Franz Schubert”
https://www.fandango.com/thedoublelifeoffranzschubert:anexplorationofhislifeandwork_v401838/summarySee here for a whole load of Schubert biographical movies / documentaries:
https://www.franzschubert.org.uk/articles/filmsch.htmlFryderyk Chopin:“A song to remember”. An incredibly miscast Cornel Wilde as Chopin. Very far from the actual facts of Chopin´s life.
Much better (and historically more accurate) is the already quoted “Impromptu” (1989), with Judy Davies perfect as George Sand and Julian Sands as a very believable Liszt. Shame about Hugh Grant as Chopin though.
“Desire for Love” (2004) - An interesting Polish movie about Chopin.
https://movies.nytimes.com/movie/314112/Chopin-The-Need-For-Love/overview “La note Bleue” – French movie (Polish director) focussing on Chopin and Sand´s relationship.
https://movies.msn.com/movies/movie-synopsis/la-note-bleue/“Jutrzenka: Un Invierno in Mallorca” (A winter in Majorca) (1971) - Spanish director Jaime Camino follows closely Sand´s book on what happened in Majorca. Historically very accurate (although Sands´s book is considered very biased).
https://movies.msn.com/movies/movie-synopsis/jutrzenka-un-invierno-en-mallorca/Franz Liszt:
“Song without end” (1947) – Dirk Bogarde as an unlikely Liszt.
https://hybrid.stanford.edu/~bayen/lisztmovies.html“Lizstomania” (1975) – Roger Daltrey miscast as Liszt in Ken Russel´s biopic.
https://www.fandango.com/lisztomania_v29484/summary Robert Schumann:“Song of Love” (1947) – Katherine Hepburn (as Clara) learned to play the piano pieces so as not to be dubbed. See a synopsis here:
https://www.geneva.edu/~dksmith/clara/clarafilms.html#SongofLove“Spring Symphony” (1983) – a more accurate biopic than the 1947 Hollywood version (and Nastassia Kinsky looks better as Clara than Katherine Hepburn).
https://www.geneva.edu/~dksmith/clara/clarafilms.html#Spring Edvard Grieg: “Song of Norway” (1970)
https://www.imdb.com/title/tt0066393/‘Edvard Grieg: What price, Immortality?” (1999)
https://www.blockbuster.com/movies/edvard-grieg-what-price-immortality.htmlClaude Debussy“The Debussy Film” (1963) – Oliver Reed plays Debussy in Ken Russel´s biopic.
https://www.screenonline.org.uk/tv/id/495009/index.html Richard Wagner :
“Magic Fire” (1955)
https://en.wikipedia.org/wiki/Magic_Fire“Wagner” (1983) – TV miniseries with Richard Burton as Wagner.
https://en.wikipedia.org/wiki/Wagner_(mini-series)
Gustav Mahler:“Mahler” (1974) Ken Russel´s hallucinatory movie.
https://movies.nytimes.com/movie/review?res=9903EFD91E3CE334BC4D53DFB266838D669EDE“Bride of the Wind” (2001) – Really about Mahler´s wife, Alma.
https://www.ravinia.org/onescore/2008/movies.htmlRichard Strauss: “Dance of the Seven veils” (1970) Another Ken Russel biopic of a composer.
https://www.screenonline.org.uk/tv/id/1030584/Vaughan Williams“Vaugham Williams” (1984) – Another Ken Russel´s biopic of a famous classical composer.
https://www.screenonline.org.uk/tv/id/1026050/index.htmlArnold Bax:
“The Secret Life of Arnold Bax” (1992) – Ken Russel´s biopic
P. I. Tchaikovsky:“The Music Lovers” (1972) - Tchaikovsky is given the Ken Russell treatment.
https://www.fandango.com/themusiclovers_v33903/summaryFrederick Delius“Song of Summer” (1968) Ken Russel biopic of Delius. Arguably the best amongst Russel´s biopics of classical composers. Watch Percy Grainger steal the scene!
https://www.screenonline.org.uk/tv/id/482807/index.htmlElgar“Elgar” (1962) – Another biopic by Ken Russel.
https://www.screenonline.org.uk/tv/id/482790/index.htmlSergei Prokofiev“Prokofiev” (1961) – Ken Russel´s biopic of the Russian composer.
https://www.screenonline.org.uk/tv/id/907277/index.htmlGordon Jacob“Gordon Jacob” (1959) – The first of the many Ken Russel´s biopics of classical composers.
https://www.screenonline.org.uk/tv/id/929027/index.htmlBela Bartok:
“Bela Bartok” (1964) Another Ken Russel biopic.
https://www.screenonline.org.uk/tv/id/907445/index.htmlPercy Grainger“Passion” - A great movie about weird Australian composer Percy Grainger (he also appears in Ken Russel´s Delius movie)
https://www.preview-online.com/may_june/feature_articles/passion/passion_pg1.html Heitor Villa-Lobos“Villa Lobos – Uma vida de paixão” (2000) - Brazilian movie director Zelito Viana made a biopic of Heitor Villa Lobos, which stays pretty close to the facts.
https://www.imdb.com/title/tt0245547/Perhaps the best music inspired movie ever made is “Tous les matins du monde” about the life and relationship of Marin Marais and his teacher Saint Coulombe, both “viol” (the precursor of the violin) virtuosi.
https://www.imdb.com/title/tt0103110/Have a look here as well:
https://pianoforum.net/smf/index.php/topic,1816.msg13689.html#msg13689(movies featuring pianists)
https://pianoforum.net/smf/index.php/topic,3454.msg30662.html#msg30662(pianos in movies)
These should get you going for a while

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Best wishes,
Bernhard