Who is considered the 'King of Ragtime' and composed 'The Entertainer'?

Scott Joplin is widely recognized as the "King of Ragtime" due to his significant contributions to the genre, particularly through his compositions that shaped and popularized ragtime music. His piece "The Entertainer," composed in 1902, is one of his most famous works and epitomizes the lively, syncopated rhythms characteristic of ragtime. Joplin’s music not only captured the essence of African American musical traditions of the time but also transcended racial and cultural boundaries, gaining popularity across diverse audiences.

His influence extended beyond just composition; Joplin also played a vital role in the development of the piano roll, making his music accessible to a wider audience. The incorporation of these elements solidified his legacy in American music history, making him a central figure in the ragtime movement. Other artists mentioned in the question, while incredibly talented in their own right and significant in different music genres, do not have the same direct association with ragtime as Joplin does.