1. Someone who seeks to draw attention to himself or herself with extravagant, attention grabbing writing: The genre of books described as "bodice rippers" are often written by sensationalists who are appealing to thrill-seeking readers.
2. Anyone who gives too much emphasis to the most shocking and lurid aspects of something: The local newspaper reporter was accused of being a sensationalist who placed too much emphasis on the coverage of the murder trial of the father who murdered his wife and three children.