The Dornier Komet, Merkur, Do C, Do D, and Do T were a family of aircraft manufactured in Germany during the 1920s, originally as small airliners, but which saw military use as well. The earliest aircraft in the series were basically landplane versions of the Delphin flying boat, and although the Delphin and Komet/Merkur series diverged from each other, design changes and refinements from one family were often incorporated into the other.
The first Komets (Do C III Komet I) utilised the wing, tail, and even upper fuselage of the early Delphin versions, but replaced the lower fuselage and sponsons with a simple sheet-metal bottom that incorporated fixed tailskid undercarriage. The engine installation was also relocated from its peculiar position above the Delphin's nose to a conventional location in the Komet's fuselage nose. Accommodation was provided for a single pilot and four passengers. An improved version, the Do Komet II, was first flown on 9 October 1922 and was widely exported to countries including Colombia, Spain, Switzerland, and the Soviet Union.