Aang

Asami

Azula

Bolin

Bumi

Ikki

Iroh

Jinora

Katara

Korra

Kyoshi

Mako

Meelo

Momo

Ozai

Pema

From India, but feels like an Irish surname (and can in fact be a variation of Rowan), so a possible cross-cultural choice. 

Rohan

Roku

As a Japanese name, Suki has the sweet meaning "loved one". It's also an English diminutive of Susanna, making it a creative and modern way to honor a Susan in your life.

Suki

Sokka

Tenzin

Toph

Ty-Lee

Zhao

Zuko

DanaeLlama's list "Avatar Names: Name your Baby as the Next Avatar" of 27 great name ideas: Aang - Zuko!

Avatar Names: Name your Baby as the Next Avatar

Eventhough it is just a show, The Last Airbender and The Legend of Korra include some of the greatest names with the most powerful and beautiful meanings. Pick some up and hope that your baby will grow up as great as these characters.