Deadwood (2004-2006)

HBO's cancellation of David Milch's profanity-laced western masterpiece remains the most agonizing cut on this list, leaving Al Swearengen's Shakespearean saga incomplete after three seasons. The network cited budget concerns, despite Deadwood averaging 3.5 million viewers per episode in its final season. Its abrupt end outranks #6's closure because the 2019 reunion film, while emotionally satisfying, could only tie up a fraction of the narrative threads. While Sense8's cancellation had similar budget issues, Deadwood's unfinished story hurts more because it was cut before its intended conclusion. The series won 8 Primetime Emmys during its run, making the financial decision even more perplexing for fans who hoped for a proper fourth season.