Count Guido Pietro Deiro (September 1, 1886 – July 26, 1950) was a famous vaudeville star, international recording artist, composer and teacher. He was the first piano-accordionist to appear on big-time vaudeville, records, radio and the screen. he usually performed under the stage-name "Deiro". Guido and his younger brother Pietro Deiro (known as "Pietro") were among the highest-paid musicians on the vaudeville circuit, and they both did much to introduce and popularize the piano accordion in the early 20th century.