Deadwood

The word "fuck" and its derivatives are used 2,980 times throughout the series.

Most of the characters (Al Swearengen, Sol Star, Reverend Smith, the Metz family, et. al., in addition to the more famous Wild Bill Hickock, Calamity Jane, and Jack McCall), have real-life counterparts.

HBO offered the chance to David Milch to wrap the series in a shorter four season, but he declined to do it on those conditions. However, when Chris Albrecht was asked about it, he said that they also told Milch that HBO would give him a full 12-episode season if it was what he needed to wrap the show. Milch told them he would think about it over a weekend, but the news about the show possibly being cancelled reached the press to such a speed that that conversation never happened