Ohakvere (Ahagfer) — knight manor in Jõhvi Parish, Virumaa County
Ohekatku (Odenkat) — knight manor in Rapla Parish, Harjumaa County
Ohukotsu (Odenwald) — knight manor in Rapla Parish, Harjumaa County
Ohulepa (Erlenfeld) — knight manor in Hageri Parish, Harjumaa County
Ohtja (Ochtjas) — support manor of Küdema manor, in Mustjala Parish, Saaremaa County
Ohtla (Ochtel) — knight manor in Kullamaa Parish, Läänemaa County
Ohtu (Ocht) — knight manor in Keila Parish, Harjumaa County
Oidremaa (Oidenorm) — knight manor in Mihkli Parish, Läänemaa County
Oisu (Oiso) — knight manor in Türi Parish, Järvamaa County
Ojasoo — look Vana-Harmi
Ojataguse (Wannamois, Oientacken) — support manor of Purdi manor, in Anna Parish, Järvamaa County
Oju (Ojo) — support manor of Paju manor, in Kihelkonna Parish, Saaremaa County
Olbrüki (Olbrück) — knight manor in Jämaja Parish, Saaremaa County
Olgina (Olgina) — support manor of Hermamäe manor, in Vaivara Parish, Virumaa County
Ollepa (Ollepäh) — knight manor in Pilistvere Parish, Viljandimaa County
Olustvere (Ollustfer) — knight manor in Suure-Jaani Parish, Viljandimaa County
Ontika (Ontika) — knight manor in Jõhvi Parish, Virumaa County
Oonurme (Onorm) — support manor of Tudulinna manor, in Iisaku Parish, Virumaa County
Oosoli (Alexandershof) — town manor in Valga Parish, Valgamaa County
Orajõe (Orrenhof) — state manor in Häädemeeste Parish, Pärnumaa County
Oraniku (Orranik) — support manor of Kaiu manor, in Juuru Parish, Harjumaa County
Orasaare (Orrasaar) — support manor of Saulepi manor, in Varbla Parish, Läänemaa County
Orava (Waldeck) — knight manor in Vastseliina Parish, Võrumaa County
Orava (Orrawa) — support manor of Kuressaare manor, in Tarvastu Parish, Viljandimaa County
Orgita (Rosenthal) — knight manor in Märjamaa Parish, Läänemaa County
Orgmetsa (Orgmetz) — knight manor in Järva-Madise Parish, Järvamaa County
Oriküla (Orriküll) — knighthood manor in Kärla Parish, Saaremaa County
Orina (Orgena) — knight manor in Järva-Jaani Parish, Järvamaa County
Orissaare (Orrisaar) — knight manor in Pöide Parish, Saaremaa County
Orjaku (Orjak) — support manor of Emmaste manor, in Käina Parish, Läänemaa County
Oru (Orrenhof) — knight manor in Lääne-Nigula Parish, Läänemaa County
Oru (Orro) — semi-manor in Jõhvi Parish, Virumaa County
Oru (Orrenhof) — support manor of Tuhala manor, in Kose Parish, Harjumaa County
Otepää (Odenpäh) — a parish in Tartumaa County
Otepää church manor (Pastorat Odenpäh) — in Otepää Parish, Tartumaa County
Otepää — look Vana-Otepää
Oti (Peudehof) — knight manor in Pöide Parish, Saaremaa County
Otsa (Otza) — support manor of Pindi manor, in Rõuge Parish, Võrumaa County