Complex sentence: Sir Arthur Ignatius Conan Doyle KStJ, DL (22 May 1859--7 July 1930) was a British writer and physician, most noted for his character Sherlock Holmes and his detective fiction, which are generally considered milestones in the field of crime fiction.
Split into simpler sentences: Sir Arthur Ignatius Conan Doyle KStJ, DL (22 May 1859--7 July 1930) was a British writer and physician, best known noted for his detective fiction featuring the character Sherlock Holmes. His Sherlock Holmes stories are generally considered milestones in the field of crime fiction.