Oh boy too many.

Zuko (found_myway)
Will Vandom (its_keeper)
Allen Gentry (twelvevoltman)
Goliath (not_philistine)
Mulan (sent_herself)
Biff (buddyofchrist)
Snotlout (the_everyviking)

And in other games OR not played yet:

Iroh (teaandlightning, lotusmaster, general_ginseng I KNOW TOO MANY JOURNALS I'LL DELETE SOME OKAY)
Lilo Pelekai (sometimes_bites)
Buzz Lightyear (buzz_al_rescate)
CAPSLOCK AVATAR KYOSHI (avatar_bigfoot)
Gollum/Smeagol (_fisshes)
God (called_i_am)
Aang (doesntneedpants)
The Avatar (aka Mirror!Aang) (forherbalance)
Molly Michon/Kendra, Warrior Babe of the Outland (flashesofmolly)
Rachel Berenson (i_mattered)
Future!Katara (southpolemaster)
Tuffnut (tuffntasteless)
Ginko (up_every_hill)
Toph (carrymyweight)
Jim Hawkins (mysolarsailpwns

Ones I don't have journals for:

Ty Lee
Julie Winters (from The Maxx)

OCs:

Irene Gentry (xenacomplex)
Duong Ashoka (withoutsorrow)
Duong Lucien (sunofasailor)
The Empress of the Sea (madrina_marina)