Wikipedia claims that the Catholic mystic St John of the Cross did not title his own poem: "The Dark Night of the Soul". If St John didn't title it who did?
The Wikipedia article (Dark Night of the Soul), to which Constantthin makes reference, says that the author of the poem, Saint John of the Cross, "wrote two book-length commentaries: The Ascent of Mount Carmel (Subida del Monte Carmelo), and The Dark Night (Noche Oscura)". So the first part of the title is already expressed by the author himself. As for the second part of the title (... of the Soul), Saint John of the Cross introduces the stanzas of his own poem with these words:
Songs of the soul rejoincing at having achieved the high state of perfection, the Union with God, by way of spiritual negation (Cançiones del alma ques se goca d'auer legado al alto estado de la perfecçion, que es la union con Dios, por el camino de la negaçion espiritual)
Whoever put the two together simply did the obvious ...