Harry Benjamin (1885–1986), German American endocrinologist and author of The Transsexual Phenomenon (1966), is often remembered as the “father of transsexualism.” He was a strong advocate for medically treating transsexual people at a time when accepted expert opinion was that being trans was a mental illness that should not be accommodated in any way.

Benjamin, born in Berlin, studied tuberculosis for his medical degree, which he received in 1912, cum laude. While a student, Benjamin met Magnus Hirschfeld, one of the leading sexologists of the early 20th century, who became a strong influence on Benjamin. Along with a senior police officer, Hirschfeld took Benjamin on tours through bars populated by people then known as homosexuals and transvestites. Benjamin also spent much time at Hirschfeld’s Institute for ...