Dr. Ulf Dietrich Merbold (born June 20, 1941) is the first West German citizen and second German native to have flown in space. He is also the first member of the European Space Agency Astronaut Corps to participate in a spaceflight mission and the first non-US citizen to reach orbit in a US spacecraft. In 1983, he and Byron Lichtenberg became the first Payload Specialists to fly on the shuttle.

In 1986, he transferred to the European Space Technology Center (ESTEC) to work on the European Columbus module for the International Space Station. Also in 1986, he became head of the Astronaut Office of the German spaceflight organization DLR. In 1988, NASA nominated Ulf Merbold as payload specialist on the IML-1 mission, which launched on STS-42 in January 1992. The following year he was Science Coordinator for the second German Spacelab mission, D-2 (STS-55).

In 1993, he also started training to fly the first of two joint European-Russian missions to the space station Mir, called Euromir 94. In 1994. During his three spaceflights he spent a total of 49 days, 21 hours and 38 minutes in space.