The Dark Half
Thad Beaumont is the writer of a highly successful set of violent pulp thrillers written under the pseudonym of'George Stark', but when he chooses to'kill-off' his alter ego in a mock ceremony, it precipitates a series of sadistic murders matching those in his pulp novels, which can be soon discovered to be the task of Stark himself. Looking like a maniacal variant of the counterpart, Stark isn't so willing to quit the writing match -- even though this means coming after his baby and Thad's wife.