Black Pope is nickname for the head of the Society of Jesus, more commonly known as the Jesuits. The name comes partly from the colour of the robes worn by members of the society and partly from a past misconception (most prominent around the 16th and 17th centuries) amongst Protestant European countries concerning the relative power of the Jesuits within the Catholic church.
On August 20 1914 both Pope Pius X and the "Black pope" died.
See also: African pope