The Finnish composer Sibelius (8 letters) is one of the most renowned and influential composers of the late 19th and early 20th centuries. He is best known for his symphonies, concertos, and tone poems, which are considered some of the most important works of the Romantic period. His music has been performed by many of the world's leading orchestras and is still popular today. He was also a noted conductor and teacher, and his influence on modern classical music is undeniable.