Obrenje - Christian Thalmann

Occidental - Edgar von Wahl

Octrin - George Schaeffer

Oda Zginzgala - Bradford Morgan White

ODODU - Jere Northrop

Odonien - Steve Oostrom

Oetadh - Pentekonter

õ’ingææ - Alex Fink

Ok - Duke Keenan

Okaikiar - Mark Reed

Oktaan

Olaetian - Herman Miller

Old Albic - Jörg Rhiemeier

Old Dwarvish - Clyde Heaton

Old Hyksos - Boudewijn Rempt

Old Kandar - Tim Hall

Old Rashurish - Ikkakujyu

Old Sindarin - J.R.R. Tolkien

Old Southern - Laurie Gerholz

Old Tongue - Robert Jordan

O'lelic - Curtis Mullings

Olijad - Robert Hill

Olvardeth - Victor Yuri Gevirtz

Omnesian - Jordan Kay

Omnial - Elx Amnial

Oneirien - Collectif Oneira

Ongaki - ACZ

Ook!

Oopee - Kelly Kozlowski|Carmen St. Jean

Oou - Sonja Elen Kisa

Opus-2 - Chris Pressey

Oraq - Mason Fraley

Orcish - Clyde Heaton

Oro Mpaa - Christian Thalmann

Ose - Thomas Leigh

Ossers/Nashi - Jan Havlis

Otg - Galivad

Ouranian-Barbaric - Peter Carroll and others

Oz - Charles Milton Elam

Ozay - Daniel Myers