K

Kaffirs
169;

Katie bar the door
8; The phrase "Katie bar the door!" (also as "Katie bar the gate!"; sometimes written as Katy) is a very American exclamation, more common in the South than elsewhere, meaning that disaster impends—“watch out”, “get ready for trouble” or “a desperate situation is at hand”. From WorldWideWords.org

Khartoum
29;

Khäutsch, Max
47; a captain in the Trabants, and field chief of K&K Special Security, who had "proven himself useful at home as an assassin"

Kimura, Mr.
29;

Klu Klux Klan ("KKK")
7; the name of a number of past and present fraternal organizations in the United States that have advocated white supremacy, anti-Semitism, racism, anti-Catholicism, homophobia, and nativism; 178; Wikipedia entry

Keeley Cure
Devised by Leslie Keeley, this was a proprietary system of treatment for the alcohol and opium habits. The Keeley Cure was a forerunner of certain measures adopted by Alcoholics Anonymous. Relying heavily on injections of Bichloride of Gold (a chemical impossibility), it was so well-known in its day that several popular songs, such as an Irish comic song, entitled "The Keeley Cure," parodied it unmercifully. More on Wikipedia

Kepler
115;

Kieselguhr Kid
171; "notorious dynamiter of the San Juans"