Minor was born in July 1834 to a prominent New England couple that had become missionaries to Ceylon. He was sent home when he was 12 years old.
Minor graduated from Yale and joined the United States Army as a surgeon. There are two stories about what major event happened next: one that he saw an Irish friend hanged, and another that during the Civil War, he was, during the Battle of the Wilderness, chosen to brand an Irish deserter who, like many others, was in the Army to train for rebellion against the English.
Aware of growing insanity, Minor left for a tour of Europe. He brought European money, his watercolor sets, a gold watch, his surgeon's commission, his letter of appointment as a captain in the U.S. Army, a letter of introduction to John Ruskin, a gun, and bullets. He slept fitfully and had an extreme fear of the Irish, especially the Fenian Brotherhood (a group of militant Irish nationalists). He insisted that they hid in the rafters and wasited for him to fall asleep, and that this happened every night. He kept his gun under his pillow.
On February 17, 1872, chasing one of these imaginary men outside with his gun, he fatally shot a man named George Merrett, on his way to work to support his family of him, his wife Eliza, (eating for two), and their 6 non-fetal children. On April 17, 1872, he was confined to the Broadmoor asylum for the criminally insane in the village of Crowthorne, Berkshire, "until Her Majesty's pleasure be known." He furnished his cell with his Army pension, buying many (mostly rare) books and spending much time painting watercolors.
At the same time, James Augustus Henry Murray was becoming editor of what would later be called the Oxford English Dictionary. Murray sent out his 4-page call for contributions to booksellers (along with many others), who put them between the pages of books, or handed them out for use as bookmarks. It was probably through the delivery of one of these that Minor learned of the project. What the OED people wanted were quotations to exemplify the use of words over time. Learning of this, Minor began to carefully index all the words in his books, a valuable collection, both financially and intellectually. When he was finished, he wrote to the OED people of what he had done. Editing a dictionary of every word in English was tiring toil, especially when you had to trudge through archaic words like "aa" and "aal" (having completed your 4-page definition of "a") before getting to "aardvark" and "aardwolf." When the editors read this letter, it was a glorious revelation. Minor had a different style than most contributors. While most would simply send in thousands upon thousands of quotations, or simply one or two, Minor would send in dozens of quotations each for the words the editors really needed help with.
Over time, he continued to keep up with the words quotations were needed for, and the editors always awaited his packages of quotations. The mysterious envelopes were addressed from "Broadmoor, Crowthorne, Berkshire." One day, a visitor commented, "How good you have been to our poor Dr. Minor." There was a sudden silence in the room. "Poor? What could you possibly mean?" The man informed them that the efficient scholar was the longest-staying inmate at the asylum. Soon, Dr. Murray and Dr. Minor became acquaintances, meeting many more times over the years and Murray introducing Minor to his family. Murray listened with pity to Minor's stories of being whisked off by airplane to Constantinople (now Istanbul) by the Fenian Brotherhood and being forced to perform lewd acts in public, but Dr. Minor was sane enough for the most part.
Minor's insanity grew worse and worse and (though this is not insanity) he became a fervent Deist. One day, in retribution for (possibly imaginary) sins in his past, he performed an autopeotomy. It might be indecent to define "autopeotomy," but let's just say that the man who performs an autopeotomy (especially in an unsterile environment with a dull pen knife) is a very brave man indeed. Minor was a surgeon, so he had some idea of what he was doing when he severed the offending object.
At this time, Minor's brother Alfred appealed to the home secretary (at the time a young man named Winston Churchill) to have William transferred to the Government Hospital for the Insane in Washington. The home secretary was slightly partial to Americans (being half-American himself) and ordered a summary of the case be sent to his office.
On April 6, 1910, Churchill signed a Warrant of Conditional Realease, the condition being that Minor "shall on his discharge leave the United Kingdom and not returnt thereto" (i.e., Minor was banished forever.) Minor was released into the custody of his brother at Tillbury Docks on April 16, 1910.
On November 8, 1918, Minor was formally diagnosed with "dementia praecox, of the paranoid form," a condition that would later be renamed to schizophrenia to dispel the negative connotations that had built up around it.
In November 1919, Minor was released from the world of insane asylums (he'd been continuously incarcerated since 1872, remember) to a hospital for the elderly insane known as the Retreat in Hartford, Connecticut, due to the efforts of his nephew Edward.
Minor died in his sleep of bronchopneumonia on March 26, 1920, at the age of 85. He is buried in the Minor family plot in Evergeen Cemetery.