James Harrison doesn't have any superpowers, but his noble act made him a colleague of comic book heroes. The Daily Mail featured Mr Harrison's story after it became known that he has been actually donating his very rare type of blood for 56 years. His simple act meant saving the lives of two million babies.

The 74-year-old Australian grandfather's plasma contains antibodies, which are vital in saving the lives of babies who are suffering from a fatal condition called Rhesus disease, a type of severe anemia, which, in the absence of blood transfusion, could mean death to the victim.

In the long run, Mr Harrison helped thousands of mothers bear healthy babies. His own daughter, Tracey, is a living witness of her dad's heroic act. She now raises a healthy son, thanks to her father's blood.

Mr Harrison started donating his blood when he was 18 years old, doing this every two weeks. So far, he has made 984 donations.

Mr Harrison's blood was considered so rare to be special that he was in fact insured for A$ 1million, thus, earning him the moniker 'man with the golden arm' or more ostentatiously the two million-dollar man.

He also enabled the development of a vaccine called Anti-D, using his blood.

Asked if he well ever stop or get tired of donating blood, his answer was a very big No.

"I've never thought about stopping. Never," he said in an interview with Mail Online.

It was revealed that Mr Harrison was just paying it forward.

When he was 14, he underwent a major chest surgery. So desperate was his condition that he needed 13 litres of blood. He was thankful for the donor that he pledged to give back by helping others.

"I was in hospital for three months," he recounted. "The blood I received saved my life so I made a pledge to give blood when I was 18."

After making his first blood donation, he learned that his blood type actually contained life-saving antibody, making him a very prized donor.

In the 1950s and 1960s, thousands of babies in Australia were victims of Rhesus disease. The disease is caused by a mismatch in the mother's blood and her unborn baby's blood. This is because one has the Rh-positive blood while the other Rh-negative.

After learning about his blood type, Mr Harrison underwent several tests so that the Anti-D vaccine will be developed.