| Crystal Brook | |
| Pushpin Map: | New York |
| Pushpin Map Caption: | Location of the mouth of Crystal Brook |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | New York |
| Subdivision Type4: | County |
| Subdivision Name4: | Delaware |
| Source1 Coordinates: | 41.9754°N -74.9913°W |
| Mouth: | Beaver Kill |
| Mouth Coordinates: | 41.9645°N -75.0043°W[1] |
| Mouth Elevation: | 1132feet |
Crystal Brook is a river in Delaware County, New York, United States. It flows into Beaver Kill northwest of Butternut Grove.