I feel that a great biography not only has to be about an interesting character, but needs to be delightful to read.

What’s the best biography you’ve read by these standards?

Atoms in The Family — great biography of Enrico Fermi (one of the most versatile physicists of the 20th century) written by his wife. Captures the “feel” of an important era in history and in the development of modern physics. 

https://a.co/d/6NAqGTn

I use Fermi-ization in my pro forecasting work. 
Did they mention the Chicago piano tuner story?