Ironic you brought up NYPD Blue because the first actor that came to mind when I read the title was David Caruso. He was great in Season 1, won the Golden Globe for Best Actor in a TV Drama and seemed a lock to win the Lead Actor Emmy, but decided he wanted a movie career and apparently was a problematic actor behind the scenes. Ended up losing the Emmy to his co-star Dennis Franz, then left the show after the first 4 episodes of Season 2. Not really fired, but seems like things weren't going to work out with Caruso had he stayed on the series.