ON SEPTEMBER 21, 1998, NBC introduced the world to Will Truman, Grace Adler, Jack McFarland, and Karen Walker. This funny fab four would become a part of TV history, garnering numerous accolades and devotees, but at the time of its premiere, Will & Grace wasn’t a surefire hit. Earlier that year, Ellen had been canceled after its titular heroine, played by Ellen DeGeneres, came out, and its tone became “too gay” for audiences. Will & Grace, then, was uncharted territory: An openly gay man had never been a protagonist on a network show. But under the stewardship of creators David Kohan and Max Mutchnick, the assured direction of veteran James Burrows, and the stellar cast of Eric McCormack, Debra Messing, Sean Hayes, and Megan Mullally, Will & Grace broke ground…