| No. | Name | Type | Language | Counties |
|---|---|---|---|---|
| 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 | EZELMA ANN OBUHORO | Master | English | Multnomah, Washington |
| 11 | RUTH NOEMI OCHOA | Master | English, Spanish | All |
| 0 | WHITNEY OCONNELL | Community | English | All |
| 22 | Soobin David Oh | Master | English | All |
| 117 | HEATHER OLEARY | Master | English | All |
| 1 | Katherine Elaine Olinger | Master | English | All |
| 0 | Yamel Olivas Solis | Standardized | Spanish | Clackamas, Multnomah, Washington, Yamhill |