Which Mars orbiter carries the HiRISE camera?

The Mars orbiter that carries the HiRISE camera is NASA's Mars Reconnaissance Orbiter.

HiRISE stands for High Resolution Imaging Science Experiment. It was designed for MRO and built by Ball Aerospace under the direction of the University of Arizona's Lunar and Planetary Laboratory. The camera launched with MRO in 2005, reached Mars in 2006, and began producing detailed images after the spacecraft completed aerobraking.

HiRISE uses a 0.5-meter reflecting telescope and can achieve roughly 0.3-meter-per-pixel resolution in favorable conditions. That power lets researchers study small geological features and monitor spacecraft hardware from orbit. It has photographed Mars rovers, landers, parachutes, dunes, seasonal changes, and proposed landing sites.

The wording can cause a common confusion: HiRISE is not itself an orbiter. It is an instrument mounted on MRO. Other Mars orbiters, including Mars Express, MAVEN, and the Trace Gas Orbiter, carry different scientific payloads and do not carry HiRISE.