You're looking in the wrong place. Television, excepting a few special cases, has yet to enter the world of higher art. Normal television series are based off the idea that people watching them are just looking for a quick fix - something to temporarily subdue the infinite and pervasive boredom of life. The shows continue until funding runs out for two simple reasons: The first, no one cares; and the second, they are profitable. When asked for series that did finish, many excellent ones come to mind, often with the thought that they actually ended prematurely. Whether this is true, or simply an effect of the barrage of utter garbage modern man is subjected to, I cannot say. If you wish for titles, the two best examples that occur to me are the Sly Cooper video game series and the Sherlock Holmes stories. The former took the form of three excellent games for the PS2, then concluded, albeit indefinitely, but mostly permanently. Many a year has passed since Sly 3 was released, and any rumors regarding a fourth installment are just that - rumors. The latter, on the other hand, has many sequels, but none by the same author, for the simple and unavoidable reason that he is currently deceased, and will remain so indefinitely. Interestingly enough, Sir Conan Doyle actually did not write Holmes stories up to his death, but instead undertook many unusual philosophical projects, most of which would today be considered lunacy. At the time, he felt that the stories were below him, and interfered with his more intelligent musings, which he believed would be the true fuel for any future fame.