Irwin Kostal (1910–2003) was an influential American conductor, arranger, and composer known primarily for his work in film and musical theater. His genre spanned classical music, film scores, and Broadway. Kostal gained prominence for his arrangements and orchestrations in various musicals, most notably for the iconic "West Side Story" (1961) and "Fiddler on the Roof" (1971), both of which earned him significant acclaim. Kostal's impact on music is particularly evident in his collaborations with legendary composers like Leonard Bernstein and Jerry Bock. He won several Academy Awards, including Best Adaptation or Original Score for "West Side Story," showcasing his talent in translating theatrical works into cinematic experiences. Additionally, he contributed to Disney films such as "Mary Poppins" (1964) and "The Jungle Book" (1967), enhancing their musical quality and accessibility. Kostal's ability to blend classical arrangements with popular music forms has left a lasting legacy, influencing generations of musicians and arrangers in both theater and film. His work continues to resonate in contemporary musical productions, underscoring the importance of orchestration in storytelling through music.