Julius Engelbert Röntgen (9 May 1855 – 13 September 1932) was a German-Dutch composer of classical music.
Julius Röntgen was born in Leipzig, Germany, to a family of musicians. His father, the Dutch born Engelbert Röntgen, was first violinist in the Gewandhaus orchestra in Leipzig; his mother, Pauline Klengel, was a pianist, an aunt of the renowned cellist Julius Klengel, born in 1859.
Julius was a gifted child. Neither he nor his sisters attended school; he was taught music by his parents and grandparents, and other subjects by private tutors. His first piano teacher was Carl Reinecke, the director of the Gewandhaus orchestra, while his early compositions were influenced by Reinecke, but also by Robert Schumann, Franz Liszt and Johannes Brahms.
In 1870, at the age of 14, Julius Röntgen visited Franz Liszt in Weimar; after playing piano for him he was invited to a soiree at Liszt's house.
In Leipzig, he and his parents were part of the musical circle around Heinrich von Herzogenberg, and it was at their house that he first met Brahms. Later Röntgen moved to Munich, where he studied piano under Franz Lachner, a friend of Franz Schubert. At the age of 18 he became a professional pianist. During a concert tour through southern Germany he became acquainted with the singer ; at this time he also met a Swedish music student Amanda Maier, whom he would marry in 1880.
In 1877 Röntgen had to make a decision whether to go to Vienna or Amsterdam. He chose Amsterdam, and became a piano teacher in the music school there. The aristocratic politician Alexander de Savornin Lohman, who was professor of law at the University of Amsterdam and an important figure in the cultural life of that city, was a friend of Röntgen's father, and he promised to take young Julius under his wing. According to Röntgen's letter of 1877 he considered the school "a place full of children and amateurs"; since the school was not supported by public funds, it appeared to attach more importance to the number of its students rather than their quality.