| # | Name | Elo | Total | Country | Rank |
| 3051. | okronos | 1552 | 1 | - | |
| 3052. | olchar10 | 2804 | 2529 | FIDE Master | |
| 3053. | old hand | 2491 | 232 | Beginner | |
| 3054. | oldhiker450 | 2275 | 446 | Talent | |
| 3055. | oldspyguy | 1610 | 16 | - | |
| 3056. | oldtop | 2053 | 12732 | Top Player | |
| 3057. | oldwilly | 2452 | 15076 |
|
FIDE Master |
| 3058. | oldwin | 1963 | 940 |
|
Shooting Star |
| 3059. | olegator73 | 2073 | 661 | Player | |
| 3060. | olga 2005 | 2666 | 7335 | Grandmaster | |
| 3061. | oliver 123 | 2322 | 11745 | FIDE Master | |
| 3062. | oliver becker | 2480 | 35815 |
|
Grandmaster |
| 3063. | oliver reeh | 2900 | 352333 | World Champion | |
| 3064. | oliverfab | 2165 | 2478 | - | |
| 3065. | olli221074 | 2105 | 1918 | Club Champion | |
| 3066. | omelnychenko | 1745 | 15 | - | |
| 3067. | omerk456 | 1926 | 120 | Beginner | |
| 3068. | omid4220 | 2790 | 3939 |
|
Grandmaster |
| 3069. | omkargopikrishna | 2344 | 174 | Amateur | |
| 3070. | omtaga | 1836 | 57 | Beginner | |
| 3071. | on passant | 1751 | 6 | - | |
| 3072. | onemunja | 2272 | 388 | Strong Apprentice | |
| 3073. | onkel3000 | 2034 | 1434 | Attacking Player | |
| 3074. | onkeljoe | 1949 | 679 | Player | |
| 3075. | onlyforyou | 1697 | 18 |
|
- |
| # | Name | Elo | Total | Country | Rank |
| 3076. | onnootje | 2550 | 6368 | Internat. Master | |
| 3077. | onshi | 1712 | 14 | - | |
| 3078. | opa304 | 2475 | 105091 | Internat. Master | |
| 3079. | optimizer01 | 2434 | 891 | Shooting Star | |
| 3080. | ordisi | 1693 | 66 | - | |
| 3081. | orejano | 1854 | 31 |
|
Beginner |
| 3082. | orhan galip ozdemir | 1712 | 14 | - | |
| 3083. | orient45 | 1726 | 57 | Beginner | |
| 3084. | orionprime | 1722 | 32 | Beginner | |
| 3085. | orlock936 | 1886 | 477 | Talent | |
| 3086. | orris2k | 1635 | 3 | - | |
| 3087. | orsito60 | 1921 | 116 | Beginner | |
| 3088. | ortwin | 2350 | 3684 | FIDE Master | |
| 3089. | osamaelwakeel | 2068 | 270 | Strong Amateur | |
| 3090. | osamaksks | 1574 | 1 | - | |
| 3091. | osmantiric | 2273 | 302 | - | |
| 3092. | osmar kohatsu | 1779 | 26 | Beginner | |
| 3093. | ostarhild | 2214 | 5850 | Master Candidate | |
| 3094. | osvalds | 2282 | 80914 |
|
FIDE Master |
| 3095. | otiliabaciu | 2453 | 4252 |
|
Internat. Master |
| 3096. | otmar miggelt | 2420 | 21634 | FIDE Master | |
| 3097. | ottawahpp | 2133 | 477 | Talent | |
| 3098. | ottogt | 2340 | 30716 | FIDE Master | |
| 3099. | ottomansaint | 2122 | 3800 | Top Player | |
| 3100. | ouadfi_anass | 2140 | 91 |
|
Amateur |