Christian Joseph Jagemann (1735, Dingelstädt – 5 February 1804, Weimar) was a German scholar, court-advisor and librarian.
Against his parents' wishes Christian became a monk, entering the Augustinian monastery at Erfurt in 1752. However, he soon fled to Denmark, where he became a private tutor. He reconciled with his parents and returned home, but then had to go to Rome and Florence as a Catholic priest. After his homecoming he joined the court of the prince of Mainz in 1774 as director of a church gymnasium in Erfurt, but lost this position the following year on the prince's death. Converting to Protestantism, in 1775 he became advisor and librarian to duchess Anna Amelia in Weimar. By his written works he promoted knowledge of the Italian old masters to Germany. His successor as librarian was Carl Ludwig Fernow.