Georges Méliès (partially found silent films from French director; 1890s-1910s)
NOTE: Because of this man's absolutely massive filmography, any information on his missing films should be put here. Nearly half of his 500+ films are still missing, many with very minimal information. This is to prevent hundreds of articles on his films, many of which would be very short and lacking information.
George Melies is often cited the "First Magician of Cinema". Starting out his career as a stage magician, he was introduced to film by its French inventors during a tour. He invested his time and money into constructing a film studio (possibly the first of its kind). Though he struggled financially at first, he went on to become one of the most successful and influential filmmakers of his time.
Melies was a special effects wizard. If he didn't invent a lot of camera and film techniques, you can almost sheerly bet he perfected or mastered them. His films have a very surreal, almost dream-like feel to them. Where other filmmakers of his time used special effects that look dated by today's standards, Melies films continue to wow audiences even in today's CGI-induced graphics.
Melies slowly fell out of popularity. By the time World War I ended, audiences had become disillusioned of his dream-like visions and George went bankrupt. He had to shut down his business and destroy most of his master negatives in order to sell the silver contained in the film to pay off his debts. It wouldn't be until close to Melies' death that his films would be recognized for their historical importance.
Of the over 500 Melies films, a grand total of 231 exist today. His films are some of the most commonly sought-after films of his era. To make matters worse, some films exist only in their black-and-white versions with many of his color versions (which were hand-tinted frame by frame) are still gone. Every now and then a film surfaces and gets remastered and cleaned up. The most recent film discovery from him is a color copy of his most treasured film A Trip to the Moon. It was found in an abandoned barn in the intense French heat, amazing many historians that it didn't ever catch on fire (as silver nitrate almost always does). New interest in his films has risen thanks to the 2011 film Hugo, which offered a (highly fictionalized) view of his life.