| Name | Location | Significance |
| Odairan Addaribantes | Ashlander Camper (SE of Molag Mar) | Hostile NPC |
| Odairan Ashummi-Ammus | Caldera Commoner (residence) | |
| Odaishah Yasalmibaal | Bensiberib Camp Ashlander | Target of a Morag Tong quest. |
| Odmi | Ashmelech Witchhunter | |
| Odral Helvi | Caldera Monk and House Brother of the Great House Hlaalu (Governor's Hall) | Trainer. Target of a quest given by Crassius Curio in Vivec Hlaalu Quarter, which will result in him giving you quests. His house is also the target of a quest given by Gentleman Jim Stacey in Vivec Foreign Quarter. |
| Odron Omoran | Molag Mar Buoyant Armiger and Novice of the Temple (Waistworks Armiger Stronghold) | |
| Ogrumbu gro-Bugarn | Valenvaryon denizen (Durz's Hut) | Hostile NPC |
| Ohibaal Assintashiran | Caldera Mine ebony miner (Caldera Mine) | |
| Oisig | Ald Daedroth denizen (Outer Shrine) | Hostile NPC |
| Okaw | Addamasartus Slave | |
| Okan-Shei | Ebonheart Savant (wandering NPC - East Empire Company Hall) | |
| Okur | Hla Oad Commoner (residence) | Target of a quest given by Kaye in Ebonheart. |
| Olank-Neeus | Habinbaes denizen | Slave |
| Oleen-Gei | Kudanat denizen | Slave |
| Olfin gro-Logrob | Ebonheart Warrior and Protector of Fighters Guild (wandering NPC) | |
| Olink-Nur | Shushan denizen | Slave |
| Olquar | Fort Buckmoth Enchanter and Initiate of the Imperial Cult | |
| Olumb gro-Boglar | Caldera Monk and Initiate of the Imperial Cult (Governor's Hall) | Trainer |
| Omesu Hlarys | Vivec St. Olms Quarter Plaza Bodyguard (Haunted Manor) | Guard of Bram Drero |
| Omni Hard-Mouth | Dagon Fel Commoner (residence) | |
| Onasha | Ebonheart Agent and Twin Lamps of the Twin Lamps (Argonian Mission) | Trainer. Head of the anti-slavery movement |
| Ondar Sarendas | Hlormaren Denizen | Hostile NPC |
| Ondi | Khuul Knight and Knight Errant of the Imperial Legion (Thongar's Tradehouse) | Trainer |
| Ondres Nerano | Balmora Hlaalu hireling (Nerano Manor) | |
| Only-He-Stands-There | Balmora Healer (South Wall Cornerclub) | Trainer, Spells, Barters potions, but none of those services will initially be available. Target of a quest given by Ranis Athrys in Balmora. |
| On-Wan | Ebonheart Slave (Argonian Mission) | |
| On-Wazei | Sinsibadon denizen | Slave |
| Optio Bologra | Gnisis Drillmaster and Recruit of the Imperial Legion (barracks) | Trainer |
| Orakh gro-Badbu | Hlormaren Denizen | Hostile NPC |
| Orbul gra-Lumob | Warrior (Dushariran Shrine) | |
| Orero Omothan | Ald Velothi Smith and Retainer of the Great House Redoran (wandering NPC ) | Repairs. Barters a couple weapons and smithing tools. |
| Oritius Maro | Gnisis Warrior of the Imperial Legion (barracks) | The target of a quest initiated by Darius of Gnisis. |
| Ormax Geles | Vivec St. Delyn Underworks Barbarian (Ihinipalit Shrine) | Hostile NPC |
| Orns Omaren | Molag Mar Trader (St. Veloth's Hostel) | Barters reagents. |
| Orrent Geontene | Ald'ruhn Nightblade and Apprentice of the Mages Guild (Mages Guild) | Spells. |
| Orval Llaren | Odirnamat denizen | Hostile NPC |
| Orvas Dren | Dren Plantation (Villa) | Target of a Hlaalu quest given by Duke Dren in Ebonheart. His support is required in order to be appointed Hlaalu Hortator. |
| Orvona Vadryon | Vivec St. Delyn Pilgrim (Abby of St. Delyn the Wise) | |
