Heinrich Schliemann - discovered Troy
Johannes Gutenberg- inventor of printing (in the west)
Sigmund Freud - started psychoanalysis
Karl Jung - psychiatrist, important in anthropology also
Werner Heisenberg - Heisenberg Uncertainty principle
Grimm brothers - folklorists (Snow White, etc) and philologists (Grimm's Law)
Franz Kafka - Ein Prozess and Die Verwandlung
Immanuel Kant (of Scottish origin

)- famous moral philosopher
Martin Luther - Theologian, began the reformation
GWF Hegel - a great philosopher
Karl Marx - needs no introduction
Ludwig Wittgenstein - another great philosopher
Karl Dönitz - U-boat admiral during WW2
.......just to name a few