A little while ago, I became curious about how the various zones of the three Dark Souls games connected to each other. I decided to satisfy this curiosity by making these graphs. When reading them, keep in mind that arrows indicate a connection, not just lines. So a line with only one arrow head is one-way only—no backtracking on foot (or via mouth, as the case may be) that way!
Note that bonfire warping is not accounted for. There would be no point in later games, after all.