By definition, humor is gentle. The savage, the cruel, the harsh would fall under the heading of wit and/or satire, as the lawyers say. Now, my definitions are these: The wit makes fun of other persons; the satirist makes fun of the world; the humorist makes fun of himself, but in so doing, he identifies himself with people — that is, people everywhere, not for the purpose of taking them apart, but simply revealing their true nature.

James Thurber (1894-1961) American humorist, cartoonist, writer

Interview (1959-03-24) by Edward R. Murrow, Small World, CBS-TV
    (Source)

When Siobhan McKenna, one of the other guests, made a comment about "cruel humor."

The transcript was printed as "That Girl in Galway" in the next (?) day's New York Post.