A look at popes and the papacy through the prism of the names associated with the popes -- whether they be birth, priestly, or assumed names. It is the first in-depth exploration of papal names and their meanings with a revised history of papal name changes, a complete account of the rationales for the 125 known instances of assumed names, and a slew of new 'factoids.' The first documented instance of papal name change was when Mercurius, in 533 A.D., opted not to introduce the name of a pagan god into the papal rolls. Marcellus II, in 1555, was the last pope, to date, to have retained his prior name, thereby breaking a 494 year tradition . 'Marcellus', however, is a name derived from 'Mars' - the Roman god of war! The history of papal name changes contains many such intriguing twists and turns, in particular Anacletus, Sixtus I, Zephryrinus and Julis II. This book sets out to highlight them all and thereby plug a hitherto little explored aspect of papal history. Despite the interest in papal names, there has been very little dedicated analysis pertaining to their evolution. Consequently, there are many inaccuracies and omissions. Papal name change could be a much older practice than originally believed. This book is an attempt to rectify the lack of attention hitherto afforded to the story and the glory of papal names. It is a by-product of a computer-aided papal history project undertaken by the author. Web site. This book is not meant to be controversial. The subject matter, though often beguiling, still does not, however, provide sufficient scope to incite bona fide dissension. This book is meant to enlighten, and hopefully entertain. With it, the author hopes to put a stake in the ground vis-à-vis our understanding of papal names.