A block is not really defined by distance, but rather is defined by the distance between cross streets, which could be 50 feet or 200 feet, depending on the place. Most blocks in cities tend to be between 200 - 300 feet apart, so the distance between 2 blocks would be roughly 400 - 600 feet.
King Piccolo: Killed by Goku. Goku prepares to put all of his strength into one single punch, but King Piccolo prepares to block it. Goku shouts "It's time for your terror to end!" and launches the punch, suddenly the image of the Great Ape appears with Goku as he flies towards King Piccolo.
Danzo killed countless people, and order the murder of even more (including the entire Uchiha clan). For highest body count I will assume Orochimaru he didn't value life and fought in the war so he killed for country pleasure and science.