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| Character | Description | Appears in |
|---|---|---|
| Ocelot | Clan Leader in Darujhistan's Guild of Assassins | GotM |
| Okral Lom | Bonecaster of the K'ron T'lan Imass, Soletaken | MoI |
| Olar Ethil | T'lan Imass Bonecaster, actually a Soletaken Eleint and Elder Goddess, possibly Burn herself | DG, MoI, DoD, CG |
| Old Hunch Arbat | Tarenthal | RG |
| Onos T'oolan | Clanless T'lan Imass warrior, former First Sword, sometimes called Tool | GotM, MoI, DoD, CG |
| Onrack | Clanless T'lan Imass of Logros | HoC, BH, RG, DoD, CG |
| Onyx | Official of the Rat Catcher's Guild of Letheras | MT |
| Orbyn 'Truthfinder' | Section chief of Patriotists in Drene | RG |
| Orenas | Tiste Liosan | HoC |
| Orfantal | Tiste Andii assassin-mage and Elient Soletaken; brother to Korlat | GotM, MoI, TH |
| Ormly | Champion Letherii rat catcher | MT, RG |
| Ormulogun | Artist attached to Onearm's Host | MoI, BH, CG |
Read more about this topic: List Of Malazan Book Of The Fallen Characters