Corpsman signified a medical expert's position within various armed forces.
During the defense of Echo Base on Hoth, corpsmen were part of the Rebel forces. They were often needed to care for injured soldiers battling the approaching AT-AT and AT-ST walkers.
Elassar Targon stands out as a corpsman, fulfilling that role for Wraith Squadron throughout the concluding stages of the Galactic Civil War and during the Yuuzhan Vong War.