5. Rocky Marciano
Breaking into the top 5 of our list is American boxer.”Rocky Marciano. Known for his relentless stamina, Marciano has one of the highest knockout-to-win percentage in heavyweight boxing history – 87.75%. He was nicknamed “The Brockton Blockbuster” and “The Rock from Brockton”. In 1969, he passed away too soon at the age of 45.