To anyone who doesn't know that Little Nell dies in the end: don't read this post. . .Whoops.

I once read a definition of tragedy and comedy.   I feel like it must've been G.K. Chesterton, but I'm also attaching Walter Scott to it, so I don't know.  The definition was simply this: in tragedy, the reader (or viewer) is constantly thinking, "They're going to make it; they're going to make it."  In the end, they do not make it.  Comedy is just the opposite.  I can cite certain examples of this, though it is far from a comprehensive definition.  A good example of this type of tragedy (let us call it a type, rather than a definition) is Romeo & Juliet.  It is one of the most famous love stories, so I'll not recap anything for the reader.  But imagine it was not so famous or imagine that you were one of the first viewers of the tragedy.  I believe the real power of the play comes from the feeling given throughout.  It is not so much that the viewer wants the young lovers to escape and be together forever, but that the story itself seems to indicate that they--if not ought to escape--will.  The fact that they don't should come as a shock.  Anyone who fancies themselves an expert on Shakespeare can disagree with me if you like.  I'm admittedly far from an expert.

Little Nell is the girl, not the old man.

An author I am--Well, perhaps not an "expert" per se, but I at least know more than the average reader.  I'll say again, slightly amended, one author I do know quite a bit about is Charles Dickens.  I also know quite a few people--literary types--who roll their eyes at the name, but the fact remains, despite their rolling eyes, that Dickens stands taller than any other figure in English literature, save the Bard himself.  And anyone who knows any substantial amount about Dickensian literature knows the controversy over Little Nell from The Old Curiosity Shop.
There is nothing exactly wrong with the character of Little Nell.  For those familier with Dickensian literature, she is fairly standard.  The innocently good--beyond-belief-good--character is seen throughout the works of Dickens and the works of many authors inspired by him.  Some other examples include, Oliver Twist, Paul Dombey, Tiny Tim, Agnes Wickfield, and even Little Dorrit.  Chesterton had a theory that Dickens based this character on someone he knew.  Perhaps it was his sister-in-law, Mary Hogarth, whom Dickens was quite attached to and was heartbroken when she died young.  Some theorize that he was in love with her.  We'll only ever have speculation on that end.  Little Nell is considered by most to be based on her, though I have see nothing from Dickens explicitly saying this.  Another theory is that it was some child he knew while working in the blacking factory who he became friends with.  Some child who died.  Dickens did not enjoy talking about those times and we know little more than he tells us.  All I know is, he wrote many characters in this style and most of them die young.  (An interesting exception is Agnes, who is of this ilk, but does not die; whereas, Dora Copperfield, née Spenlow, does die young, but is not of this type of character.  She represents young love and is based on a girl Dickens' admired as a young man.  I will perhaps post further about Dora, Agnes, and their parallel characters from Little Dorrit.)
Of course, with all this talk of people dying, it is probably made clear that Little Nell dies.  This is where the controversy arises.  At the time, people all over the world were devastated by the news.  We've all heard the story of people in New York City flooding the docks to ask sailors from England, who might have read the last installment of The Old Curiosity Shop, if Nell had lived.  At the time it was considered a truly moving tragedy.
That opinion has become part of a heavy debate among Dickensians as well as foes of Dickens.  I won't go so far as to agree with Oscar Wilde and say that her death should incite tears of laughter, but I will say that her death seems out of place with the story.  It seems forced.
Perhaps that is because Dickens didn't have her death planned until later in the book, after he'd heard that his fans expected it.  Now, if there's one thing Dickens liked to do, it was please his fans.  He loved his readers and they loved him for it.  Now, it's also possible that Dickens didn't ever plan on keeping her alive.  I've only just tonight heard that he had planned it, but haven't found the evidence for it yet.  Either way, there is a definitive shift in the novel where one begins to expects Nell to die.  Not because the story calls for it, but the attitude of the author seems to change.  He begins to treat her with something more than pity, which he holds for her throughout the novel.  It's not so much that this aura isn't there, as it is the question of whether it should be or not.  Little Nell dies, yes, but should she?  She seems a makeshift tragic heroine.

Now, I realize this was Dickens first real attempt at tragedy--the books before this were comedies expect for Oliver Twist--and Nell death is not going to be as masterfully done as, say, Sydney Carton.  His was a truly moving death.  Nell's death, however, seems pointless.  She dies at the end simply to die, as a sacrifice to the bloodthirsty author--Dickens killed people with the indifference of a pagan god.  He clearly improved as an author, and despite Little Nell, The Old Curiosity Shop is filled with a wide cast of wonderfully done characters--customers, I almost want to say.  It's hard to find a better villain in all of Dickens' novels than Daniel Quilp, and Dick Swiveller is one of the most lovable of Dickens' rascals.  Also, I know that regardless of my, and many people's, opinion that Little Nell should have lived, people will still read The Old Curiosity Shop and cry at the end.  That's fine.  For the sake of honesty, I'll admit it: I cried at the end too.