Johannes Brahms (; German: [joˈhanəs ˈbʁaːms] ; 7 May 1833 – 3 April 1897) was a German composer, virtuoso pianist, and conductor of the mid-Romantic period. His music is noted for its rhythmic vitality and freer treatment of dissonance, often set within studied yet expressive contrapuntal textures. He adapted the traditional structures and techniques of a wide historical range of earlier composers. His œuvre includes four symphonies, four concertos, a Requiem, much chamber music, and hundreds of folk-song arrangements and Lieder, among other works for symphony orchestra, piano, organ, and choir.

Born to a musical family in Hamburg, Brahms began composing and concertizing locally in his youth. He toured Central Europe as a pianist in his adulthood, premiering many of his own works and meeting Franz Liszt in Weimar. Brahms worked with Ede Reményi and Joseph Joachim, seeking Robert Schumann's approval through the latter. He gained both Robert and Clara Schumann's strong support and guidance. Brahms stayed with Clara in Düsseldorf, becoming devoted to her amid Robert's insanity and institutionalization. The two remained close, lifelong friends after Robert's death. Brahms never married, perhaps in an effort to focus on his work as a musician and scholar. He was a self-conscious, sometimes severely self-critical composer.

Though innovative, his music was considered relatively conservative within the polarized context of the War of the Romantics, an affair in which Brahms regretted his public involvement. His compositions were largely successful, attracting a growing circle of supporters, friends, and musicians. Eduard Hanslick celebrated them polemically as absolute music, and Hans von Bülow even cast Brahms as the successor of Johann Sebastian Bach and Ludwig van Beethoven, an idea Richard Wagner mocked. Settling in Vienna, Brahms conducted the Singakademie and Gesellschaft der Musikfreunde, programming the early and often "serious" music of his personal studies. He considered retiring from composition late in life but continued to write chamber music, especially for Richard Mühlfeld.

Brahms saw his music became internationally important in his own lifetime. His contributions and craftsmanship were admired by his contemporaries like Antonín Dvořák, whose music he enthusiastically supported, and a variety of later composers. Max Reger and Alexander Zemlinsky reconciled Brahms's and Wagner's often contrasted styles. So did Arnold Schoenberg, who emphasized Brahms's "progressive" side. He and Anton Webern were inspired by the intricate structural coherence of Brahms's music, including what Schoenberg termed its developing variation. It remains a staple of the concert repertoire, continuing to influence composers into the 21st century.