There were so many heroes on June 6, 1944 that it is not right to single out any individual or group.
From the lunatic glider troops of the British 6th Airborne Division securing the Pegasus Bridge at 0016 hrs in Operation Deadstick, the pilots landing within yards of their objective, in freakin' gliders!, with a skill that Sir Trafford Leigh-Mallory, the commander of Allied air forces, would later praise as the finest feat of flying in the entire war.
The parachutists of the 82nd Airborne jumping into Sainte Mere Eglise at 01:30, where Pvt. John Steele found his place in history when his parachute got caught on the church steeple and he hung wounded for two hours before the Germans cut him down (he escaped).
The German privates in the bunkers and pillboxes at dawn, looking out at the largest armada ever assembled-
6939 vessels: 1213 naval combat ships, 4126 landing ships and landing craft, 736 ancillary craft and 864 merchant vessels.
Most of them said something that included the word Scheiße (exkrement).
(One German officer purportedly said, in disbelief, "It's impossible ... there can't be that many ships in the world." )
At 06:30 the 2nd Ranger Battalion scaling Pointe du Hoc's 100 foot cliffs under fire using ropes and ladders.
Those are some of the famous stories, and there are hundreds more.
The archetypal image though, is the beach landing, with this being one of the most famous pictures of the war:
That's a Higgins boat with troops of 1st Infantry Division (The Big Red One) on Omaha Beach.
From a 1964 interview with Supreme Allied Commander General Dwight Eisenhower:
"'Andrew Higgins..'..Eisenhower said..'..is the man who won the war for us.' My face must have shown the astonishment I felt at hearing such a strong statement from such a source. Eisenhower went on to explain, 'If Higgins had not designed and built those LCVPs, we never could have landed over an open beach. The whole strategy of the war would have been different.'"
-Stephen E. Ambrose
D-DAY JUNE 6, 1944: THE CLIMACTIC BATTLE OF WORLD WAR II
As one writer put it:
...It wasn't very big, it wasn't blindingly fast, it wasn't brimming with big guns, and it most definitely wasn't heavily armored. In fact, it was made primarily of wood.
But the Higgins Boat was one of the most decisive weapons utilized by the Allies during World War II. The only real dispute is whether it should be classified as a weapon.Mr. Higgens ended up running a pretty big operation, over 20,000 employees manufacturing the landing craft and PT boats. Here's a factoid:
It differed greatly from other tide-turning developments, such as the British Spitfire fighter plane, the Russian T34 tank, and the American P51 Mustang fighter. While the boat was equipped with a pair of .30 caliber machine guns, it was not an instrument of destruction....
...In September, 1943, when the United States Fifth Army landed at Salerno, Italy, and General Douglas MacArthur's forces captured Salamaua in New Guinea, the American navy totaled 14,072 vessels. Of these boats, 12,964, or 92% of the entire U.S. Navy, were designed by Higgins Industries, Incorporated; 8,865 were built at the Higgins plants in New Orleans, La....This landing craft was in on every major D-Day invasion of the war. Normandy, North Africa, Sicily, Italy, and the islands of the Pacific: Guadalcanal, Tarawa, Saipan, Tinian, Iwo Jima and Okinawa.
Here's the site of the Higgins Memorial in Columbus Nebraska, Higgens' boyhood home, a long way from the beaches of Normandy.
Eisenhower Takes Responsibility for the Failure of the D-Day Landings