Julius Ernest Wilhelm Fučík (Czech: [ˈjulɪjus ˈfutʃiːk]; 18 July 1872 – 25 September 1916) was a Czech composer and conductor of military bands. He became a prolific composer, with over 400 marches, polkas, and waltzes to his name. As most of his works were for military bands, he is sometimes known as the "Bohemian Sousa".

Today his marches are still played as patriotic music in the Czech Republic. His worldwide reputation rests primarily on two works: "The Florentiner March", popular throughout much of Europe, and the "Entrance of the Gladiators" (Vjezd gladiátorů), which is widely recognized, often under the title "Thunder and Blazes", as one of the most popular theme tunes for circus clowns.

Fučík was the brother of opera singer and bass player Karel Fučík and uncle of the journalist Julius Fučík, who was executed by the Nazis.