Ludwig van Beethoven (baptized 17 December 1770] – 26 March 1827) was a German composer and pianist. A crucial figure in the transition between the Classical and Romantic eras in Western art music, he remains one of the most famous and influential composers of all time.

Born in Bonn, then the capital of the Electorate of Cologne and part of the Holy Roman Empire, Beethoven moved to Vienna in his early 20s, studying with Joseph Haydn and quickly gaining a reputation as a virtuoso pianist. His hearing began to deteriorate in his late twenties, yet he continued to compose, conduct, and perform, even after becoming completely deaf.

Beethoven was bedridden for most of his remaining months, and many friends came to visit. He died on Monday, 26 March 1827, during a thunderstorm. His friend Anselm Hüttenbrenner, who was present at the time, claimed that there was a peal of thunder at the moment of death. An autopsy revealed significant liver damage, which may have been due to heavy alcohol consumption.

Beethoven's funeral procession on 29 March 1827 was attended by an estimated 20,000 Viennese citizens. Franz Schubert, who died the following year and was buried next to Beethoven, was one of the torchbearers. Unlike Mozart, who was buried anonymously in a communal grave (the custom at the time), Beethoven was buried in a dedicated grave in the Währing cemetery, north-west of Vienna, after a requiem mass at the church of the Holy Trinity (Dreifaltigkeitskirche). His remains were exhumed for study in 1862, and moved in 1888 to Vienna's Zentralfriedhof.

There is dispute about the cause of Beethoven's death; alcoholic cirrhosis, syphilis, infectious hepatitis, lead poisoning, sarcoidosis and Whipple's disease have all been proposed. Friends and visitors before and after his death clipped locks of his hair, some of which have been preserved and subjected to additional analysis, as have skull fragments removed during the 1862 exhumation. 

Some of these analyses have led to controversial assertions that Beethoven was accidentally poisoned to death by excessive doses of lead-based treatments administered under instruction from his doctor.