One hundred years ago—in 1908—Archibald Garrod delivered his four Croonian Lectures. In these formerly forgotten, but now famous, dissertations, Garrod first used the expression, ‘inborn errors of metabolism’, to describe four rare disorders: albinism, alkaptonuria, cystinuria, and pentosuria. This prescient work proposed that such disorders resulted from enzymatic defects in the catabolic pathways for amino acids and sugars. Thus, Garrod can rightfully be called the first human geneticist. Much influenced by his colleague Bateson, who brought Mendel’s work to his attention, Garrod then was the first to apply Gregor Mendel’s law of gene segregation to humans, the first to propose recessive inheritance in humans, and the first to point out the importance of consanguinity. He even mentioned the role of ethnicity in inherited disorders. This would have been legacy enough, but Garrod did much more. He wrote about such other ‘modern’ topics as genetic predisposition to common disorders; the critical importance of physicians who were also scientists; and the proper role of the university in society. Although Garrod’s work and ideas were not appreciated during his lifetime, they have echoed and reverberated ever since. He can rightly be deemed one of the most profound intellectuals of the 20th century, whose bequests to science and medicine continue to increase in value. All of us who study inborn errors of metabolism and who apply our knowledge in the hope of improving the diagnosis and treatment of affected patients are, in a genuine sense, Garrodians.