| Big Nellie Mountain | |
| Location: | Taree, New South Wales, New South Wales, Australia |
| Elevation M: | 542 |
| Type: | Rhyolite[1] or Trachyte[2] |
| Age: | Miocene |
| Map: | Australia New South Wales |
| Label Position: | left |
| Map Size: | 250 |
| Coordinates: | -31.7006°N 152.5222°W |
Big Nellie Mountain is a volcanic plug in the Mid North Coast region of New South Wales, Australia. It is situated northeast of Sydney, within Coorabakh National Park.