* denotes Presenting Author
| Oare, Courtney | WE-E-TRACK 6-3* |
| Oba, Hiroshi | PO-GePV-M-56 |
| Obeid, Jean-pierre | PO-GePV-M-257 |
| Obuchowski, Nancy | TU-D-TRACK 4-0* |
| Och, Joseph | MO-F-TRACK 3-0*, MO-F-TRACK 3-0*, TH-IePD-TRACK 2-4 |
| O'Connell, Dylan | PO-GePV-M-54, PO-GePV-M-136, PO-GePV-M-190, PO-GePV-M-255, SU-F-TRACK 6-3, MO-IePD-TRACK 3-3, MO-IePD-TRACK 4-5, WE-IePD-TRACK 3-2 |
| O'Connell, Jericho | WE-IePD-TRACK 1-5*, TH-E-TRACK 3-6 |
| O'connell, Nicole | MO-IePD-TRACK 3-1 |
| O'Connor, Michael | SU-EF-TRACK 2-0* |
| Oderinde, Oluwaseyi | PO-GePV-T-222*, PO-GePV-T-223*, PO-GePV-T-304*, PO-GePV-T-422*, TH-F-TRACK 3-3 |
| Odisio, Bruno | MO-A-TRACK 6-2, TU-E-TRACK 6-3 |
| Oeffinger, Kevin | TU-A-TRACK 6-5 |
| O'Farrell, Desmond | PO-GePV-T-17, WE-C-TRACK 3-3, TH-E-TRACK 5-6 |
| Ogawa, Kazuhiko | SU-IePD-TRACK 5-2 |
| O'grady, Kyle | PO-GePV-T-163 |
| Oguma, Kohei | PO-GePV-M-39* |
| Ogunmolu, Olalekan | SU-D-TRACK 4-7* |
| Oh, Jung Hun | PO-GePV-M-11*, TH-F-TRACK 4-1 |
| Oh, Kyuhak | PO-GePV-E-23, TH-C-TRACK 5-7* |
| Oh, Seungjong | PO-GePV-M-78, PO-GePV-M-180, TH-B-TRACK 6-3, TH-F-TRACK 6-3* |
| Ohashi, Haruna | PO-GePV-M-130, MO-IePD-TRACK 4-2, MO-IePD-TRACK 4-7 |
| Ohno, Takeshi | PO-GePV-I-24 |
| Ohri, Katherine | PO-GePV-T-153, WE-IePD-TRACK 6-3 |
| Ohri, Nisha | PO-GePV-T-360 |
| Ohri, Nitin | SU-E-TRACK 5-7 |
| Ohrt, Andrea | TU-IePD-TRACK 3-6 |
| Ohrt, Jared | SU-IePD-TRACK 6-4, TU-IePD-TRACK 3-6 |
| Ohta, Atsushi | PO-GePV-T-337 |
| Oinam, Arun | PO-GePV-T-30 |
| Oita, Masataka | PO-GePV-M-212 |
| Okazaki, Keita | PO-GePV-M-158* |
| Olanrewaju, Adenike | PO-GePV-E-23, PO-GePV-T-193, SU-A-TRACK 6-1, SU-F-TRACK 5-2, MO-IePD-TRACK 5-6, TH-C-TRACK 5-7, TH-E-TRACK 4-3 |
| Olberg, Sven | PO-GePV-M-148, MO-EF-TRACK 4-5, TH-IePD-TRACK 3-5 |
| Olcott, Peter | WE-IePD-TRACK 3-5, TH-F-TRACK 3-3* |
| Oldham, Mark | PO-GePV-T-439, TU-B-TRACK 2-4, TU-IePD-TRACK 6-7, TH-D-TRACK 5-4 |
| Olguin, Edmond | PO-GePV-I-1, WE-D-TRACK 3-2 |
| Oliver, Daniel | TH-IePD-TRACK 3-2 |
| Olivera Velarde, Daniela | PO-GePV-T-436*, TU-IePD-TRACK 1-6* |
| Olsen, Jeffrey | PO-GePV-T-139 |
| Olson, Timothy | TU-IePD-TRACK 1-7 |
| Olsson, Jimmy | PO-GePV-M-36 |
| Omachi, Chihiro | PO-GePV-T-90 |
| Omari, Eenas | PO-GePV-M-74, PO-GePV-M-90, WE-C-TRACK 6-7 |
| Omidi, Alireza | MO-IePD-TRACK 1-2* |
| Onda, Kiyoshi | PO-GePV-T-337 |
| Ong, Yihong | PO-GePV-M-58, PO-GePV-T-402*, SU-IePD-TRACK 6-1, WE-IePD-TRACK 3-2 |
| Ono, Shigeto | TU-EF-TRACK 4-8 |
| Ono, Tomohiro | MO-IePD-TRACK 5-4*, WE-IePD-TRACK 6-7* |
| Onochie, Ifeanyirochukwu | PO-GePV-M-243, TH-E-TRACK 4-2 |
| Oraiqat, Ibrahim | TH-C-TRACK 6-5* |
| Orbach, Darren | TU-IePD-TRACK 2-7 |
| O'reilly, Dedri | PO-GePV-M-4 |
| O'Reilly, Shannon | PO- -Virtual-3*, PO-GePV-T-107*, TU-IePD-TRACK 5-3, WE-IePD-TRACK 3-3 |
| Orio, Peter | PO-GePV-T-17 |
| Orlando, Nathan | WE-F-TRACK 3-2*, WE-IePD-TRACK 1-2 |
| Orlik, Corey | TU-A-TRACK 2-3 |
| Orton, Colin | SU-EF-TRACK 7-0*, SU-EF-TRACK 7-0* |
| Osgood, Greg | TH-E-TRACK 3-4 |
| O'Shea, Michael | TH-IePD-TRACK 2-4 |
| Oshika, Riki | PO-GePV-T-90, PO-GePV-M-103* |
| Osman, Alexander | TH-F-TRACK 5-3 |
| Osmundson, Evan | WE-IePD-TRACK 6-5 |
| Ostergren, Kyle | WE-SHOWCASE-TRACK 8-12-1* |
| Osterman, K. Sunshine | PO-GePV-M-122*, MO-A-TRACK 1-0*, WE-IePD-TRACK 6-6 |
| Ostyn, Mark | PO-GePV-T-419 |
| Osunbayo, Olaolu | PO-GePV-I-2* |
| Otazo, Ricardo | WE-D-TRACK 6-3, TH-IePD-TRACK 3-7 |
| Ourselin, Sébastien | SU-F-TRACK 5-4 |
| Ove, Roger | PO-GePV-T-18 |
| Overshiner, Brian | SU-IePD-TRACK 6-7 |
| Owen, Daniel | TU-C-TRACK 4-3, TU-C-TRACK 4-4 |
| Owen, Graham | PO-GePV-M-110, PO-GePV-T-182 |
| Owens, Constance | SU-IePD-TRACK 3-4, TU-A-TRACK 6-2*, TU-A-TRACK 6-5 |
| Owens, Michael | PO-GePV-M-246, PO-GePV-T-329 |
| Own, Ahmed | PO-GePV-E-2 |
| Oya, Megumi | TH-IePD-TRACK 3-2* |
| Ozawa, Shuichi | PO-GePV-T-188 |
| Ozer, Mustafa | PO-GePV-P-41 |