Ernst Georg Ferdinand Küster (November 2, 1839 - April 19, 1930) was a German surgeon born in Wollin.
He studied medicine in Bonn, Würzburg and Berlin, and following graduation became an assistant to Robert Ferdinand Wilms (1824-1880) at the Bethanien Hospital in Berlin. In 1875 he became habilitated for surgery, and in 1879 was an associate professor and chief physician at Berlin's Augusta Hospital. In 1890 he was appointed professor of surgery at the University of Marburg, and in 1907 returned to Berlin as a surgeon.
In 1872 Küster was a founding member of Deutsche Gesellschaft für Chirurgie (German Society of Surgery), and in 1903 was its chairman. He is credited for developing the foundation of modern radical mastoidectomy for treatment of chronic ear disease. Küster's radical mastoid operation is described as an extension of the simple mastoidectomy introduced by otologist Hermann Schwartze (1837-1910).