Final answer:
Ludwig van Beethoven is the composer known for incorporating new orchestral instruments such as the piccolo and contrabassoon, especially in his later works which heralded the Romantic era.
Step-by-step explanation:
The composer known for incorporating new orchestral instruments such as the piccolo and contrabassoon is Ludwig van Beethoven. Beethoven was pivotal in transitioning between the Classical and Romantic eras. He began his career with works that were classical in style but his later music became emblematic of the Romantic era's expressive and expansionist trends. Beethoven's music is recognized for its innovation, including his use of expanded orchestras with new instruments to create a rich, full sound. This allowed for the exploration of new sonic territories and greater emotional expression in music.
The Romantic era itself was marked by composers like Brahms, Tchaikovsky, Schumann, Schubert, Chopin, and Wagner, yet what distinguishes Beethoven is his progressive use of the orchestra's potential. His symphonies, in particular, employed a larger variety of instruments compared to his predecessors, and this legacy influenced many composers who followed, including the likes of Berlioz, Strauss, and Wagner, who were also known for challenging contemporary musical boundaries.