<blockquote><font class="small">In reply to:</font><hr /><p>I guess if he runs out of regenerations (what is his limit again?) - they could explain a change by the Doctor being dissatisfied with his new appearance and undergoing plastic surgery.<p><hr /></p></p></blockquote><br /><br />He can regenerate twelve times, which means he has a total of thirteen lives. (The one he was born with, plus the twelve he regenerates into.)<br /><br />There's an old joke in Who fandom.....<br /><br /><i>What goes bang, thud, bang, thud, bang, thud, bang, thud, bang, thud, bang, thud, bang, thud, bang, thud, bang, thud, bang, thud, bang, thud, bang, thud, bang, thud?<br /><br />A Time Lord commiting suicide.</i><br /><br /><img src="/images/icons/tongue.gif" /><br /><br />Actually, the twelve regeneration limit wasn't set until the episode "The Deadly Assasin". (And it bothered a lot of fans at the time; that episode explored the Doctor's past and the planet Gallifrey in far greater detail than had ever been done before. It's a fan favorite now, but it wasn't then. It's interesting how perspectives change with time.) In that one, the Master apparently commits suicide -- and it's permanent because the Doctor explains that this is the Master's thirteenth body. (Of course, the Master isn't really dead, but I won't go into any more detail lest I spoil the episode for somebody. <img src="/images/icons/tongue.gif" /> )<br /><br />The Master did of course acquire additional bodies after that. In "The Keeper of Traken", he steals the body of Consul Tremas. (I suppose fans should've expected that; after all, Tremas is an anagram of Master. Doctor Who has always had a curious love for anagrams.) That happens at the very end of the episode, but as it happens after the resolution of the basic plot, I don't think I'm ruining it for anybody. He kept that body for years (and it curiously seemed to become somewhat Time Lordish, since although Tremas was Trakenite, the Master makes a remark in "The Mark of the Rani" <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em> -- The Tenth Doctor, "Blink"</font></p> </div>