Who ran through the city naked shouting , "Eureka"?

He was a Sicilian of course! This great scientist and mathematician noticed how water displaced  when bathing at the bath house; giving him the answer to a problem he was solving for the King .  So excited about his discovery, he "streaked" through Siracusa shouting "Eureka, Eureka...."

Archimedes (287-212 BC) developed weapon systems that made Syracuse impenetrable, founded the value of pi , invented Archimedes Screw (still used today), Archimedes Principles of buoyancy and displacement, and countless other inventions.  Working on a solution for finding the area in a circle, he established the foundation that would later become calculus. His ideas were adopted by scientist such as DaVince, Galileo, and Newton.

One day, he was interrupted by a Roman soldier in his study.  In an absent minded fashion he berated the soldier.  Not realizing this crazy old man was Archimedes, soldier killed him with his sword.

Read more about Archimedes and his manuscript that sold for $2 million.  Wiki  has excellent summary and references.