The name Cosette is a girl's name of French origin meaning "little thing". Cosette and is often added to lists like Literary Names for Girls and discussed in our forums with posts like "Picky Parents BNG".
From the experts:
Cosette is best known as the heroine of Les Miserables. In the Victor Hugo novel, Cosette was the nickname given to the girl named Euphrasie by her mother. Although Hugo invented the name, some etymologists believe it's a spin on Colette, originally a female short form of Nicolas.
Despite the popularity of Les Mis the musical, the name was given to only 138 girls in 2015 -- though it's worth noting that this is almost double the number from just a few years ago. Cosette would make a sweet if coquettish French choice.