| Name | Type | Language | Counties |
|---|---|---|---|
| RUTH NOEMI OCHOA | Master | English, Spanish | All |
| TRISTA MICHELLE OCHOA | Master | All | |
| WHITNEY OCONNELL | Community | English | All |
| CATHERINE ANN OEHLER | Master | English | Clackamas, Multnomah, Washington |
| Soobin David Oh | Master | English | All |
| HEATHER OLEARY | Master | English | All |
| Katherine Elaine Olinger | Master | English | All |
| Yamel Olivas Solis | Standardized | Spanish | Clackamas, Multnomah, Washington, Yamhill |
| Diane Lynn Olney | Community | English | Washington |
| ELIZABETH ANN OLSON | Standardized | ||
| EUNICE BEVERLY OLSON | Standardized | English | Jackson, Josephine |
| Laura Ann Olson | Master | English | Clackamas, Marion, Multnomah, Polk, Yamhill |
| LINDA OLSON | Standardized | English | Umatilla |
| Kim (Kiki) Omoto | Master | English | Benton |
| CHRISTINA SUZANNE ONEILL | Master | English | All |
| LISSET ONEILL | Master | English, Spanish | Multnomah |
| Nancy L Orem | Master | English | All |
| RAUL DAVID OROZCO FUENTES | Master | English, Spanish | Benton, Linn, Marion, Polk |
| ANA LAURA ORTEGA | Standardized | Hood River, Wasco | |
| Kay Guadalupe Ortega | Standardized | English, Spanish | Jackson, Jefferson, Josephine, Klamath |