Colusa or Colusi may refer to:
People Colusa Indian Community, a Wintun tribe
Places Colusa, California, county seat of Colusa County Colusa County, California Colusa County Airport, California Colusa County Courthouse, California Colusa, Illinois Colusa National Wildlife Refuge, California Colusa Rancheria, California Colusa Unified School District, California
Other Colusa grass, a common name of Neostapfia colusana, the sole species within the genus Neostapfia