| Greenhill River | |
| Pushpin Map: | Canada Ontario |
| Pushpin Map Caption: | Location of the mouth of the Greenhill River in Ontario |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Ontario |
| Subdivision Type3: | Region |
| Subdivision Name3: | Northeastern Ontario |
| Subdivision Type4: | District |
| Subdivision Name4: | Algoma |
| Source1: | Greenhill Lake |
| Source1 Location: | Makawa Township |
| Source1 Coordinates: | 48.5864°N -83.8681°W |
| Source1 Elevation: | 396m (1,299feet) |
| Mouth: | Missinaibi River |
| Mouth Location: | Hayward Township |
| Mouth Coordinates: | 48.7214°N -83.4522°W |
| Mouth Elevation: | 286m (938feet) |
| River System: | James Bay drainage basin |
| Tributaries Right: | South Greenhill River |
The Greenhill River is a river in Algoma District in northeastern Ontario, Canada.[1] It is in the James Bay drainage basin, and is a left tributary of the Missinaibi River.
The river begins at Greenhill Lake in geographic Makawa Township[2] and flows north, curving around the west side of the lake to eventually head southeast to Amik Lake. It continues south east then northeast through the north central part of geographic Amik Township,[3] then enters geographic Nebotik Township at the southwest corner. The river continues northeast, then turns east and takes in the right tributary South Greenhill River. It continues east, enters geographic Conking Township,[4] turns northeast, enters geographic Hayward Township,[5] flows under the Canadian National Railway transcontinental railway main line between the railway points of Fire River to the west and Argolis to the east, a section of track travelled on by Via Rail transcontinental Canadian passenger trains, and reaches its mouth at the Missinaibi River. The Missinaibi River flows via the Moose River to James Bay.
The entire course of the river, except for the short portion downstream (to the north) of the CN mainline, is within the Chapleau Crown Game Preserve. That remaining short portion is within Missinaibi Provincial Park.