Franz Liszt
The Hungarian Franz Liszt is considered by many to be the most talented pianist of all time. Also a very prominent composer, Liszt wrote an etude called La Campanella, which is now used as a challenge of dexterity among very talented and aspiring performers alike. Here Evgeny Kissin demonstrates his unbelievable technical skills with the most impressive performance of this piece (or, indeed, any other) that I've ever seen: