Karl Bernhard Woldemar Ferdinand von Ditmar was a Baltic German geologist and explorer, who travelled in and contributed to the scientific understanding of Kamchatka.

Karl von Eckartshausen was a German Catholic mystic, author, and philosopher.

Friedrich Wilhelm Karl, Ritter von Hegel was a German historian and son of the philosopher Georg Wilhelm Friedrich Hegel. During his lifetime he was a well-known and well-reputed historian who received many awards and honours. He was one of the major urban historians during the second half of the 19th century.

Karl Eduard von Holtei was a German poet and actor.

Karl von Prantl was a German philosopher and philologist.

Karl Ritter von Scherzer was an Austrian explorer, diplomat and natural scientist.

Karl Gotthelf Jakob Weinhold was a German folklorist and linguist who specialized in German studies.

Karl Wilhelm Ferdinand Solger was a German philosopher and academic. He is known as a theorist of Romanticism, and of irony.

Karl Wilhelm Fricke is a German political journalist and author. He has produced several of the standard works on resistance and state repression in the German Democratic Republic (1949–1990). In 1955 he became one of several hundred kidnap victims of the East German Ministry for State Security, captured in West Berlin and taken to the east where for nearly five years he was held in state detention.

Karl Wilhelm Nitzsch was a German historian known for his studies of ancient Rome and medieval Germany. He was the son of classical philologist Gregor Wilhelm Nitzsch (1790–1861).