Norman van Lennep vs M Nauhaus
9th German Chess Congress Leipzig GER 1894.09.??
Ruy Lopez: Old Steinitz Defense, Semi-Duras Variation 1-0

O Nukolenko vs Varlam Vepkhvishvili
Kaunas Cup round 5 1988.07.19
Blackburne Shilling Gambit 1-0

O Rostovtsev vs Nikolay Dmitrievich Grigoriev
Kislovodsk Kislovodsk URS 1928.08.??
Queen’s Indian Defense: Capablanca Variation 0-1

Octavio Figueira Trompowsky de Almeida vs Walter Oswaldo Cruz
BRA-ch Rio de Janeiro BRA round 7 1938.02.??
Nimzo-Indian Defense: Sämisch Variation, Accelerated 1/2-1/2

Oladapo Oluto Adu vs Omar Eltigani
FIDE Online Olympiad Chess.com round 7 2020.08.02
Queen’s Gambit Declined: Hastings Variation 0-1

Olaf Dobierzin vs Herbert Bastian
GER-ch Gladenbach GER round 7 1997.11.23
Sicilian Defense: O’Kelly Variation 0-1

Olafur Thorsson vs David Bronstein
Reykjavik Open Reykjavik ISL round 1 1996.03.02
King’s Indian Defense: Exchange Variation 0-1

Oldrich Duras vs Hugo Suechting
Prague Prague AUH round 5 1908.05.23
Ruy Lopez: Berlin Defense 1-0

Oleg Korneev vs Ivan Cheparinov
XI Anibal Open Linares ESP round 6 2005.03.01
Sicilian Defense: Najdorf Variation 1/2-1/2

Olga A Andreieva vs Bronislava Mosionzhik
6th Soviet Team Cup Riga URS 1968.12.??
Sicilian Defense: Dragon Variation, Yugoslav Attack, Belezky Line 1/2-1/2