Corpsman was a rank used in several militaries to denote a medical specialist.
History
Corpsmen served in the Rebel defenses protecting Echo Base on the planet Hoth. They were frequently called upon to see to wounded soldiers fighting the incoming AT-AT and AT-ST walkers.
A notable corpsman was Elassar Targon, who served in that capacity for Wraith Squadron through the latter years of the Galactic Civil War and the Yuuzhan Vong War.