Charles, one of the most beloved musicians of all time, had no shortage of unreleased music to draw from after his death in 2004 at the age of 73. Most recently, his estate released "Rare Genius" in 2010, comprised entirely of previously unreleased songs and demos from the '70s, '80s, and '90s.
The first album by Charles to be released posthumously was 2005's "Genius & Friends," which is made up of unreleased duets between Charles and his friends, like Gladys Knight, Diana Ross, Willie Nelson, and John Legend, among others.