Final answer:
P.T. Barnum, before becoming a circus showman, published a newspaper and was arrested for libel. He later opened a museum that featured hoaxes like the Feejee Mermaid.
Step-by-step explanation:
The individual who, before running off to run the circus, published a Danbury newspaper and was arrested for libel is a. P.T. Barnum. Before P.T. Barnum became famous for his traveling circus, he was successful in other ventures such as a museum owner. His American Museum in New York City included exhibits with many oddities, one being the "Feejee Mermaid," which he advertised as real. However, this exhibit was not a genuine mermaid but a fabricated creature, a composite of a monkey and a fish.