Ziri O. -- Val Ontell

1. O., Ziri (2)
2. Oakes, Ron (3)
3. Oakes, Tara (3)
4. Oakley, Annie (4)
5. O'Bar, Rob (5)
6. O'Brien, Beth (3)
7. O'Brien, Hal (7)
8. O'Brien, Kevin
9. O'Brien, Terry
10. O'Brien, Ulrika (6)
11. Oceana, Esteban (2)
12. Oceanna (2)
13. Ochipinti, Dan
14. Ochoa, Johan
15. O'Connell, Consuelo
16. O'Connell, Jennifer (2)
17. O'Connell, Michael
18. O'Connell, Wendy
19. O'Conner, Grayson (2)
20. O'Connor, Dea
21. O'Connor, Edward (2)
22. O'Darrow, Heather (4)
23. Odayashi, Kyra (4)
24. Odbert, Elspeth
25. Odbert, Jim
26. O'Deay, Jerry (2)
27. O'Dell, Tom
28. O'Donnell, Abby (3)
29. Ofoegbu, Ike
30. Oggy (2)
31. Ogre (6)
32. Oh, Stan (80)
33. O'Halloran, Christina (14)
34. O'Halloran, John (19)
35. O'Hanlon, Rod
36. O'Hare, Dorothy (2)
37. Ohlde, Robert
38. Ohlson, LeraRae
39. Ohlson, Nancy (2)
40. Okamura, David (5)
41. Oki-Dogs
42. Okkami, Paige (2)
43. Okum, Allan (4)
44. Oldroyd, Paul (13)
45. Oliansky, Ingrid (12)
46. Oliver, Gloria (2)
47. Oliver, John W. (4)
48. Oliver, Kathie (8)
49. Oliver, Thomas (16)
50. Oliver, Tom (2)
51. Olsen, David
52. Olsen, John
53. Olsen, Karina (2)
54. Olsen, Kim
55. Olsen, Tammy
56. Olson, Bill
57. Olson, Erik V. (90)
58. Olson, Glen (96)
59. Olson, Janis (115)
60. Olson, Jonathan (43)
61. Olson, Mark (18)
62. Olson, Priscilla (20)
63. O'Malley, Matt
64. O'Meara, Jennifer (2)
65. Ondoy, Carlo (9)
66. One, Surly
67. O'Neil, Paul (2)
68. O'Neil, Raven (9)
69. O'Neill, Dave (2)
70. Oniko
71. Ontell, Ron (36)
72. Ontell, Val (24)

Anthony Orantes -- Ozzy

73. Orantes, Anthony (2)
74. O'Rear, Victor
75. Orenstein, Liz
76. Organ-Kean, Margaret
77. O'Riley, Rod (24)
78. Orochimaru (41)
79. Oropallo, Brandon
80. Oropesa, Samatha (3)
81. Orozco, Erik
82. Orr, Jordan (3)
83. Orr, Marilee (7)
84. Orrock, Alec (6)
85. Ortega, Alex
86. Ortega, Angel
87. Ortega, Manuel
88. Ortega, Riley
89. Ortega, Vicki (2)
90. Orth, Jeff (13)
91. Ortiz, Erica (5)
92. Ory, Alex
93. Orzechowski, Tom
94. Osborn, Phil
95. Osborne, Cary (7)
96. Osborne, Heather (6)
97. Osborne, Jason (4)
98. Osborne, Jonathan
99. O'Shea, Chris (6)
100. O'Shea, Dick (2)
101. O'Shea, Kaity (5)
102. Oshins, Keith (2)
103. Osier, Henry (2)
104. Ostro, Marie (3)
105. Ostro, Shelley (2)
106. Oszko, Lance (2)
107. Ota, Jayme
108. Otakon (2)
109. Otero, Marvin
110. O Tuama, Aodh Og
111. Oun, Charlie
112. Oung, Miky (0)
113. Outlaw, Da (40)
114. Ouw, Nadia (2)
115. Ouw, Shirley (2)
116. Ovary, Madame
117. Overton, Kathi (7)
118. Ovitt, Alexandra (2)
119. Owen, Brandi
120. Owen, Caroline (9)
121. Owen, Eric (3)
122. Owen, Ralph (8)
123. Owens, Kendra
124. Owens, Scott
125. Owings, Jul (5)
126. Owings, Mark (2)
127. Oxford, Helen (3)
128. Oyama, Noriko (2)
129. Oyster, Royster T. (2)
130. Ozbun, Robert
131. Ozzy (3)

23 first names

Oceanna Oggy Ogre Oki-Dogs Okie Ol' Olivia Omaha Omar One Oniko Ophelia Orange Oren Orenda Orlando Orletta Orochimaru Orson Oscar (3) Otakon Ozgun (2) Ozzy