Inception

The most contemporary film on this list, it's debatable as to whether or not this ending is even a twist; depending on your interpretation, it may just be a needlessly ambiguous tag on an already-complex thriller. But waiting for that top to stop spinning in the final moments of Christopher Nolan's Inception opens up such a Pandora's Box about what is or isn't real about the film that it has retroactively devastated everything that came before it - there are some who even argue that none of the film is real. For that reason alone it makes it onto this list, and we'll likely be debating the outcome (and relevance) of that top for decades.