In the play 'Antigone', Theban King Creon is tragic, because of how his life ends. He thinks that he can order his life and the lives of his family and indeed of the entire Theban society. He thinks that he can separate the emotions out of life and issue laws that violate the god-given rules by which Thebans make their way through life into death. For example, he thinks that he can deny proper burial to the disloyal Theban dead in oppositon to the assurance of that right by divine laws. He thinks that such a heartless law can be enfoced without any thought to the pain and suffering of the law-abiding loved ones that the dead leave behind in Thebes.
So in the end, everything that gives the King's life meaning is taken away from him. He scorns the feelings of Thebans who cannot bury their dead under his laws. And so he finds out what it's like to have a dead son and a dead wife. He scorns the feelings of his own niece, Antigone, and blithely sentences her to death. His treatment is so cruel that Antigone commits suicide by hanging herself with her own halter. And so the King finds out what it's like to have loved ones take their own lives. In fact, that's exactly how his son and his wife die. They prefer to face eternal death than one more minute above ground under his insensitive rules.
And, finally, the King loses his kingdom. He thinks that he can rule without any influence or input from those he rules. He thinks that he can order Theban society in the way that he wants. But he finds out his ultimate powerlessness in the face of the combined weight of Theban tradition, public opinion, and god-given laws when they all are turned against him. In the end, therefore, King Creon is tragic, because he's left with nothing. He has no family, no friends, no future, no home, no kingdom, no respect.