Yeah you can. Although most of the time only some “rights” are sold while others are retained. A great example is the major DC Comics heroes. The copyright history of Superman and the associated storyline and characters is pretty educational on the subject. And that history there still doesn’t include everything. If you watch the original 1978 Superman movie, you’ll notice it as a “Ilya and Alexander Salkind” production. (Not Warner Bros.) That’s because at that point in time, Alexander owned the rights. And there’s a whole history there, of that transition to WB gaining ownership.
And most recently, you’ve got this:
Warner Bros Has Lost Krypton; Will Lose Superman in 2013
Warner Bros. So Distraught Over Losing Superman Rights, It Personally Sues The Lawyer Who Won
In fact, as you might expect, all the big characters have troubled IP histories. (A lot of money in that kind of monopoly).
But yes, as you can see, technically you can sell IP rights, but it doesn’t mean there won’t be any dispute about it. The bottom line is the only guarantee is court time is wasted on nonsense, and lawyers get rich.
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