She was certainly the least famous of the sisters - although it's be hard for anyone to compete with Marguerite of Valois, the Pearl of France.
In one of the books I read on Mary, Queen of Scots it said she was particularly close to Claude: they had been raised together and continued sending letters to each other until Claude's death in 1575.
Claude was only 27 at the time of her death but had already given birth to 9 children. Among her direct descendants are:
- King Juan Carlos of Spain
- Albert II of Belgium
- Margrethe II of Denmark
- Grand Duke Henri of Luxembourg
- Prince Hans-Adam of Liechtenstein