Librettist W.S. Gilbert (1836–1911) and Arthur Sullivan (1842–1900) comprised the most well-known and well-loved Victorian Era partnership. (Probably the most famous theatrical partnership ever!)  The two men collaborated on fourteen comic operas between 1871 and 1896, including the three most loved and played, H.M.S. Pinafore, The Pirates of Penzance and The Mikado.
 
Gilbert, who wrote the words, is loved for his fanciful stories. Sullivan composed the music, contributing melodies that showed his humorous side as well as his emotional side.
 
Because Gilbert and Sullivan were so captivating, and provided such awe-inspiring operas, G&S Societies popped up all over the world during the early 1900s. Many of those Societies are still around today and create major productions of Gilbert and Sullivan’s work.

For a wealth of G&S information start here:

http://math.boisestate.edu/gas/