Barannfin,
That honour goes to Floyd Carlson (just), Bell Helicopter's test pilot, who carried out a rescue on 5 Jan 1945.
Bell's chief test pilot (fixed wing) baled out of a stricken YP-59 jet fighter and parachuted 10,000 ft into a remote area and deep snow. Although injured and having lost his flying boots, he made it to a farmhouse but no vehicle could get to him. Carlson took off in helicopter ship No 2, picked up a doctor, and made it to him in time to treat his injuries and save the loss of his toes. An ambulance made it to him three hours later behind a snow plough.
But, if this rescue was technically not an evacuation by helicopter, that happened a short time later in March 1945.
Carlson rescued two fishermen stranded on breaking ice in the middle of Lake Erie. Before leaving base, Carlson experimented with a mechanic to determine the right fuel load and weight and balance to ensure he could pick up a man from the hover without settling. He then rescued the fishermen one at a time after they'd spent 21 hours on the ice.
So endeth the history lesson!