Thomas Starzl, the man who performed the world's first liver transplant, has died days short of his 91st birthday, BBC reported.
The American surgeon pioneered the procedure in 1963, but his first patient did not survive.
After creating a new blend of anti-rejection drugs, he carried out the first successful transplant in 1967. Since then, thousands of lives have been saved by the procedure.
He died at home among his family, a spokesperson said.
In a statement, the University of Pittsburgh, which he joined in the 1980s to work on his drugs research, said Dr Starzl was known as the "father of transplantation" for his work in advancing the surgery from "from a risky, rare procedure to an accessible" one.