(Please, James Bond fans, tell me that there is a Great Blofeld Controversy! I'd hate to think that you were the only sub-group of fandom that didn't have a hotly debated, never-settled question to bicker over during the long winter nights.)
For those of you who aren't James Bond fans (or just in case there is no Great Blofeld Controversy and I need to start it) please, let me explain. Ernst Stavro Blofeld is widely considered to be James Bond's arch-nemesis, despite the fact that in all of the movies where the two met each other face to face, the same pair of actors never played Bond and Blofeld. (In fact, the only actor to play Blofeld twice was the uncredited voice actor who played the part in his first two appearances, "From Russia With Love" and "Thunderball".)
Bizarrely, although Bond's changes in actor are never given an in-story explanation (apart from George Lazenby's aside to the camera, "This never happened to the other fellow," at the start of "On Her Majesty's Secret Service") Blofeld's constant transformations are explained away as the result of plastic surgery for one reason or another. Not only does he change his face to avoid the law, he also uses doubles that have been surgically altered to resemble him as surrogates and decoys.
Which leads to the question, "How can we be sure that Blofeld is really Blofeld every time?" Sure, it'd be nice to assume that anyone saying he's Blofeld is actually Blofeld unless proven otherwise (like the two doubles killed in "Diamonds Are Forever") but this isn't actually the theory that fits the facts best. Let's go through his appearances and see.
In the twenty-two "canonical" Bond films, Blofeld appears six times. The first two, "From Russia With Love" and "Thunderball", never show his face. Instead, his only signifying feature is his pet cat, which he strokes while ordering his sub-ordinates around in an emotionless tone. Here, he appears humorless, ruthless, and precisely calculating in every detail of his complex plans.
In his third appearance, "You Only Live Twice", he is played by Donald Pleasance, and finally meets Bond face to face. He's bald, short, and has a dueling scar down his right eye and cheek. This Blofeld is consistent with his previous two appearances, and there's really no reason to assume it isn't the genuine article.
The next film, "On His Majesty's Secret Service", has Blofeld played by Telly Savalas. He's lost the scar and made a few other minor changes (actually, Savalas is the best physical fit for Blofeld in the books, although Fleming's original character wasn't bald.) The changes are explained away as plastic surgery necessary to fit in with the physical appearance of the Bleauchamp family line; Blofeld plans to claim the title and estates, and needs to make sure he looks like a Bleauchamp. (Also, it's worth mentioning that this movie provides the clearest--though still very weak--evidence that Bond's appearance is supposed to be changing with the change in actors. Bond plans to infiltrate Blofeld's lair disguised as a genealogist, but he doesn't change his appearance at all, despite having met Blofeld face to face. Clearly, we're meant to assume that Blofeld will be looking for Sean Connery.) This Blofeld is a little more wry and sardonic, but not inconsistent with his previous appearances. But most notably, he suffers a serious neck injury escaping from Bond via bobsled...when we last see him, he's being driven away from a crime while wearing a neck brace.
Then we get "Diamonds Are Forever". In this movie, Blofeld is played by Charles Gray, and he's got his hair back, he's taller, and his mannerisms, speech patterns, and modus operandi have all changed. In fact, he's almost a camp version of his former self; whereas the Blofeld of the earlier movies was almost like a living computer of crime, this Blofeld admits that he "doesn't understand all the science" of his current scheme, and is quite garrulously chatty with Bond. (Which is actually one of the best moments of the film. "What's your plan this time, Blofeld?" "Oh, you know that as soon as I'm ready to explain it, James, you'll be the first to know. But it's late, I'm tired, and I've got lots to do. Can I show you out?" "What's this?" "It's a lift, James. It goes down.") This Blofeld is also the first to openly use doubles on screen. He seemingly perishes in an explosion at the film's conclusion.
Finally, in the opening to "For Your Eyes Only", we see a mysterious bald man in a wheelchair wearing a neck brace, stroking a pet white cat and planning an elaborate death for Bond. His face is never seen, but he bears a vicious and personal grudge against Bond, and strikes at him at a place and time that holds great personal significance between the two men. It's pretty clear that this is once again Bond's arch-nemesis, Ernst Stavro Blofeld. Bond dispatches him by dropping him into an open smokestack.
So what's the controversy? Simply that I don't think the Blofeld in "Diamonds Are Forever" was really Blofeld. He doesn't act like Blofeld, he doesn't look like Blofeld, he doesn't talk like Blofeld, he admits to having plastic surgery-altered doubles wandering around, and most importantly, when we next see Blofeld, he looks the same as he did at the end of "On Her Majesty's Secret Service". Occam's Razor tells us that the simplest solution is most often correct. So either Blofeld recovered from his broken neck with miraculous speed, altered his whole appearance with plastic surgery, dreamed up an elaborate scheme involving lasers from space, executed it in a way that was nothing like his usual M.O., then got injured in a way that removed his hair and left him with another broken neck...or he hid out while recuperating, and had a trusted lieutenant act in his stead to throw Bond off the scent. Which makes more sense?
Either way, it seems pretty likely he didn't survive the fall into the smokestack. So for now, it's kind of a moot point, unless they decide to revive the character for the "rebooted" Bond 23. (Which isn't likely, because there are niggling rights issues related to the curious status of "Thunderball" as a co-owned production. It's the same weirdness that led to Sean Connery returning as Bond in "Never Say Never Again".) But I at least hope to find out whether anyone but me actually cares.