The main character, the raison detre, of Doctor Who is unlike any other television protagonist in terms of the sheer amount of mystery: Recall that for six full seasons right through most of second Doctor swansong "The War Games", audiences had essentially no idea whatsoever of his origin. We first saw his home planet in season 10 ("The Three Doctors"); the name of said planet was only given in its 14th year of running (Deadly Assassin). We went through full-on nine versions of the character before we knew anything concrete of his childhood, not to mention of his relationship with his most persistent nemesis, The Master (The Sound of Drums). And just another 50 years passed before we got more of our hero's life before he began adventuring ("The Name of the Doctor") And how little we still know about the man ... it's part of the fascination that's enthralled for decades. Particularly in the shows modern era, however, we fans have become impatient with tying up loose ends; witness uberfan/show producer Steven Moffats efforts to clean everything of the 11th Doctors era up in the recent trilogy of stories seeing out Matt Smith. Yet despite the ever-longer reach into the shows history and expansion of canon, at least a few storylines are doomed to go forever unresolved. Forget learning the Doctor's name -- you know that's never gonna happen. WhatCulture instead presents a few of the more compelling (read: maddening) mysteries on following pages.