(Latin: "the very simplest", superlative of simplex)
German satirical weekly magazine, founded 1896 by Albert Langen (1869-1909) and the artist Thomas Theodor Heine (1867-1948).
Simplicissimus became a trend-setting, internationally acclaimed political publication, with contributions by Heinrich and Thomas Mann, Rainer Maria Rilke and Hermann Hesse, among others. It featured illustrations by Heine, Bruno Paul, Olaf Gulbransson, Ragnvald Blix and Anton Hansen.
During World War I, Simplicissimus functioned as a pro-war propaganda magazine, but it later regained its satirical style, which it retained until it was closed down by the Nazi censors in 1944.
Under a new name, Der Simplicissimus, it was again published from 1954, but closed in 1967, never to return.
Apatrix points out, quite rightly, that "perhaps one could attribute the name to the influence of 'Der abenteuerliche Simplicissimus Teutsch' (1668)". I agree with this conjecture (having made it myself), but none of my sources indicate any such connection.