Any clues about what kind of biography you'd like to read? Explorers, musicians, actors, politicians, ... there's a lot of choice.
A few I've liked:
The worst journey in the world - written by a man (Aspley Cherry-Gerrard) who was on Scott's expedition to the S. Pole.
P.G. Wodehouse A biography (by Donaldson) - probably only of interest if you're a Wodehouse fan.
Frida: A biography of Frida Kahlo (Herrara) - I have no liking of her art at all but I enjoyed this book.
Also, I know they're for kids but I absolutely love all the Little House on the Prarie series. It is fascinating to me to read about how life was back then (albeit in a highly sanitised sense).