Which tight end is known by the nickname "Gronk"?

Which defensive lineman was nicknamed "The Minister of Defense"? Which Bears defensive tackle was nicknamed "The Refrigerator"? Which Chicago Bears legend was known as "The Galloping Ghost"? Which quarterback was nicknamed "The Gunslinger"? Which Steelers quarterback was nicknamed "Big Ben"? Which running back, nicknamed "Kansas Comet," starred for the Bears in the 1960s? What was the nickname of the Pittsburgh Steelers' 1970s defense? What was the nickname of the Minnesota Vikings' 1970s defensive line?