Sergey Nurenberg (1864–1933) – a journalist, public figure, official. >>

Georgy Obushev (1929–2020) – Doctor of Engineering Sciences (Dr. sc. ing.), Associate Professor of the Faculty of Electricity of the Riga Technical University. >>

Pyotr Odintsov (1891–1968) – a Full Member of  Latvian  Academy of Sciences, an authority in chemical technology of wood material. >>

Irina Odoyevtseva (1895–1990) – a poet and author of memoirs. Born in Riga into the family of lawyer Gustav Heinike. >>

Alexander Ogurtsov (1939–2017) – a lawyer for defence. >>

Vasily Oknov (1830–1894) – Russian Orthodox priest, archpriest, translator and publisher of liturgical books, including in Latvian. >>

Nikolai Adamovich Okolo-Kulak (1867–1927) – a mechanical engineer, inventor, state councilor, head of the main Riga workshops of the Riga-Oryol railway, founder and director of the Russian Technical School in Riga. >>

Boris Oks (1928–2012) – Habilitated Doctor of Engineering, professor of the Riga Technical University. >>

Vladimir Okun (1943) – a soloist of the Latvian Opera, director.

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Alexander Olbik (1939-2018) – a journalist and writer. >>