Muhammad Ali (born Cassius Marcellus Clay Jr.; January 17, 1942 – June 3, 2016) was an American professional boxer, activist, entertainer and philanthropist. Nicknamed The Greatest, he is widely regarded as one of the most significant and celebrated figures of the 20th century and as one of the greatest boxers of all time. Ali was born and raised in Louisville, Kentucky. He began training as an amateur boxer at age 12. At 18, he won a gold medal in the light heavyweight division at the 1960 Summer Olympics and turned professional later that y…