Chlorinda

Chloris

Clarissa, the daintier version of Claire, has a long literary history of its own, having been featured in the novels of Samuel Richardson, Charles Dickens, and Virginia Woolf—Clarissa was the title character of Mrs. Dalloway—not to mention the 1990s teen sitcom, Clarissa Explains it All. 
 Clarissa is a name definitely worth considering as an alternative to the overused Vanessa and Melissa. Appealing diminutives are Clarry and Claris.
 Red Cross founder Clara Barton was born Clarissa.

Clarissa

Attached in Irish mythology to a Cliona who was, among other things, an inspirer of poets. Cliona is well-used in modern Ireland, along with Irish form Cliodhna, though it's largely unknown in the rest of the world.

Cliona

Clothilda

Pronounced klo-TEELD, this name is well used in France, but rarely heard here; it has a chic and sophisticated air.

Clothilde

Old and aristocratic European name that would be tough for an American kid to pull off. 

Clotilda

A romantic rarity, derived from the Old German name Chlotichilda, meaning "famous in battle." Saint Clotilde was a Frankish queen, wife of Clovis I, who played a role in the spread of Christianity.

Clotilde

Clove is a spice name that is a tad more piquant than Saffron or Cinnamon. It might get more attention now as a member of The Hunger Games family of names.

Clove

Chlodmira 

Chlodomira

Chlodoviga

Chlodowig

Chlodowiga

Chlodwiga

Chlotara

Chlotichhilda

Chlotsuintha

Chlotswintha

Chlowiga

Clarimond

Clarimonda

Clothild

Clotsinda

Clova

Clovia

Cloviga

Clovisa

Clowiga

BlairX's list "Chlo/Clo names that sound stronger than Chloe" of 29 great name ideas: Chlorinda - Clowiga!

Chlo/Clo names that sound stronger than Chloe

Note: these don't come from the same root word as Chloe. Chlo/Clo is also a root word found in old Germanic names, which most of these come from.