If you don't know who he is, what are you doing here?
Fine, I'll tell you.
Peter Jackson is the New Zealand-based film director who struck big with his film adaptations of The Lord of the Rings. The three movies were all nominated for multiple Oscars, with The Return of the King eventually winning him the Best Picture and Best Director Oscar, among numerous other prizes, making it the first fantasy film to win the Best Picture Oscar.
There has been much controversy over Jackson's portrayal of the Rings trilogy—some fans feel Jackson nailed the series, while others feel that Jackson put in too much stuff that wasn't in the books, left out too much stuff, or at least left out the wrong stuff, and portrayed in a weird manner what he did include. These criticisms usually stem from the removal of Tom Bombadil from the first movie, Saruman seemingly disappearing without a trace in Return of the King, changing some (or, depending on your opinion, most) of the characterizations, and the now-infamous Flaming Denethor incident.
It is also Jackson's adaptation of the trilogy that single-handedly led to a revival in the popularity of the works of J.R.R. Tolkien, which also led to, by proxy, a severe increase in LotR badfic, mainly perpetrated by Suethors who take the movieverse to heart and have massive, unhealthy crushes on the leading men, especially Orlando Bloom (who plays Legolas) and Viggo Mortensen (who plays Aragorn). Depressingly, there has not yet been a recorded Suefic with John Rhys-Davies/Gimli as the lust object.
Jackson has also crafted some other great films, including The Frighteners (Michael J. Fox plays a paranormal investigator up against the Grim Reaper), Heavenly Creatures (the Gilliam-esque, disturbing true story of two girls who plot to kill one of the girls' mother), and the 2006 remake of King Kong. Check them out if you can (and like PJ).