Cecil Sharp
Cecil James Sharp (22 November 1859 – 23 June 1924) was the leading figure in the early twentieth century folk revival in England. He collected (and published) a huge number of songs, tunes and dances; and although modern critics have sometimes attacked his methods or his attitudes, there are few who would not admit that - flawed product of his age though he undoubtedly was - we are very much the richer for the work which he did.
You can read more about some of the controversies surrounding Sharp, and revisionist attempts to restore his reputation, in an article on the Musical Traditions website: Jumping to Conclusions Mike Yates examines a row that is bubbling away beneath the surface of British folksong scholarship.
For a fuller biography see:
Michael Heaney, ‘Sharp, Cecil James (1859–1924)’, Oxford Dictionary of National Biography, Oxford University Press, Sept 2004; online edn, May 2006 http://www.oxforddnb.com/view/article/36040
or the Wikipedia article on Cecil Sharp.