| No. | Name | Type | Language | Counties |
|---|---|---|---|---|
| 0 | Frank Thomas O'Hearn | Standardized | All | |
| 2 | Christina Suzanne O'Neill | Master | English | All |
| 1 | ERIN JEAN O'REGAN | Master | English | Multnomah |
| 1 | Amie O'Rourke | Master | English | Benton, Linn |
| 0 | Kimberly Diane O'Shaughnessy | Community | English | Crook, Deschutes, Jefferson, Klamath |
| 0 | EZELMA ANN OBUHORO | Master | English | Multnomah, Washington |
| 11 | RUTH NOEMI OCHOA | Master | English, Spanish | All |
| 0 | TRISTA MICHELLE OCHOA | Master | All | |
| 0 | WHITNEY OCONNELL | Community | English | All |
| 0 | CATHERINE ANN OEHLER | Master | English | Clackamas, Multnomah, Washington |