The song "What One Man Can Do" (by John Denver) was sung about a person.
Who is that person?
Buckminster Fuller (1895-1983).
This assertion (without accredation) shows up in a variety of places: wikipedia, a thesis (pg 16), a sermon (pg 7).
More authoritatively is this anthology (pg 152-153) about Fuller, and this article from people magazine in 1980 on occasion of Denver performing the song for Fuller:
...Denver proposed "my toast to Bucky." John had composed it especially for the event, and his guests, touched and teary-eyed, joined in the chorus: "What one man can do is dream/What one man can do is love/What one man can do is change the world and make it new again." Then John Denver kissed the grand old man, stroked the back of his neck and murmured, "I love you, Bucky."