More than 60 years ago, his life was saved by the kindness of strangers. He's been returning the favor ever since.
They call him "the man with with golden arm," and he's saved the lives of more than 2 million babies.
Rhesus disease is a potentially deadly condition where a pregnant woman's blood attacks the blood cells of her fetus.
It's caused when a rhesus-negative (RhD negative) mother is carrying a rhesus-positive (RhD positive) fetus. Usually, these women are able to give birth to completely healthy children. But in certain cases, the mother may be sensitized to RhD positive blood, leading to the disease.
One man has been helping fight rhesus disease for more than 60 years.
His name is James Harrison, and he's a really tough guy.
No, not Pittsburgh Steelers linebacker James Harrison. I'm sure he's plenty tough, but I'm talking about a different James Harrison.
This is the James Harrison I'm talking about:
His blood carries rare, powerful antibodies that have helped doctors develop an injection to help fight rhesus.
And every week, Harrison heads down to donate more of his powerful, life-saving blood.
Roughly 17% of pregnant women in Australia are at risk of developing rhesus disease.
Medical experts have estimated that James Harrison has helped save more than 2 million babies from rhesus disease.
When he was 14, Harrison's life was saved in part by the blood of strangers, prompting his decision to donate himself.
He had a lung removed in 1951. He told CNN that a conversation with his dad helped him decide to pay it forward:
"When I came out of the operation, or a couple days after, my father was explaining what had happened. He said I had [received] 13 units (liters) of blood and my life had been saved by unknown people.
He was a donor himself, so I said when I'm old enough, I'll become a blood donor."
— James Harrison