| West Branch Dead Diamond River | |
| Pushpin Map: | New Hampshire#USA |
| Pushpin Map Size: | 250 px |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | New Hampshire |
| Subdivision Type3: | County |
| Subdivision Name3: | Coos |
| Subdivision Type4: | Town and township |
| Subdivision Name4: | Pittsburg, Atkinson & Gilmanton Grant |
| Length: | 2.7miles |
| Source1: | Confluence of Roby Brook and Rowell Brook |
| Source1 Location: | Pittsburg |
| Source1 Coordinates: | 45.0164°N -71.1717°W |
| Source1 Elevation: | 1460feet |
| Mouth: | Dead Diamond River |
| Mouth Location: | Atkinson & Gilmanton Grant |
| Mouth Coordinates: | 45.0025°N -71.1486°W |
| Mouth Elevation: | 1438feet |
| Tributaries Left: | Middle Branch Dead Diamond River |
| Tributaries Right: | Cascade Brook |
The West Branch of the Dead Diamond River is a 2.7adj=midNaNadj=mid[1] river in northern New Hampshire in the United States. It is a tributary of the Dead Diamond River, located in the Androscoggin River watershed of Maine and New Hampshire.
The West Branch of the Dead Diamond River rises in a southern corner of the town of Pittsburg, New Hampshire, at the juncture of Rowell and Roby brooks. Flowing southeast, it passes into the township of Atkinson and Gilmanton Academy Grant, where it joins the East Branch to form the Dead Diamond River. The Middle Branch of the Dead Diamond joins the West Branch shortly before the West and East branches join.