I am the greatest!!
You'd probably think of "I'm the Greatest", the song written by John Lennon for Ringo Starr in his 1973 'Ringo' album but I am thinking more about Muhammad Ali, born Cassius Marcellus Clay Jr., the American boxer who 'float like a butterfly and sting like a bee'. The Heavyweight Champion of the World for three times between 1964 and 1979 had said he was the greatest. Even then, he was a victim of Parkinson's Disease.