The Hansa-Brandenburg D.I, also known as the KD (Kampf Doppeldecker) was a German fighter aircraft of World War I.

Despite poor handling characteristics it was put into service by Austria-Hungary, where some aircraft served until the end of the war.

[1] The KD had a deep fuselage, which gave a poor forward view for the pilot and tended to blanket the small rudder, giving poor lateral stability and making recovery from spins extremely difficult.

[6] The D.I was the standard fighter aircraft of the Luftfahrtruppen until mid 1917, being used by several Austro-Hungarian air aces such as Godwin Brumowski and Frank Linke-Crawford.

[5] Some Phönix built D.Is remained in use until the end of the war, being used briefly by the armed forces of The Republic of German Austria (Republik Deutschösterreich), where they were used to fight Yugoslav attacks on Klagenfurt in Carinthia.