A collapsible reflective optical sight for a firearm includes a base that mounts the optical sight to the firearm, a lens attached to and rotatable with respect to the base, wherein the lens includes a first optic with a reflective surface and the lens is folded with respect to the base for storage in a collapsed configuration and is angled with respect to the base in a deployed configuration for use in aiming the firearm, a light source on the base that reflects light off the reflective surface of the first optic to a user for aiming the firearm, and a mechanical sight on the base for aiming the firearm when the lens is in the collapsed configuration.