Sir Arthur Conan Doyle, from the Library of Congress Flickr photo stream. The photo apparently dates from 1913 or thereabouts. I always imagined Conan Doyle as a less modern, more Victorian character than this — more like Holmes.
Flickr has lots of wonderful vintage images like this one, not all book-related obviously. I recommend the streams of the Library of Congress, the Smithsonian, and the George Eastman House for starters, but there are lots more. If you find any needles buried in those haystacks, do let me know.