The Fokker Dr.I Dreidecker (triplane) was a World War I fighter aircraft built by Fokker-Flugzeugwerke.
The Dr.I saw widespread service in the spring of 1918. It became renowned as the aircraft in which Manfred Von Richthofen gained his last 19 victories, and in which he was killed on 21 April 1918.
So who is this Von Richthofen you ask? There was a movie made of him called The Red Baron.
He is the famous fighter plane pilot who excelled during his era killing many great ranking enemies. He was regarded as a national hero in Germany, and was very well known by the other side.