Unicorns are mythical, except when they're real. During 1906, the 1930s and the 1980s, living unicorns - their signature single horns cultivated by humans, rather than by either magic or genetic anomalies - both walked the earth and hit the news.
Early 1900s: Unicorn Rams at the London Zoological Gardens
These two unicorn barwal rams were among a large collection of exotic Nepalese animals given as a ceremonial gift to the Prince of Wales and quartered in the London Zoo. Skulls of similar unicorn rams had been presented to the British Museum in 1845, but these were probably the first living representatives of their kind to have been seen outside of Nepal.
At the time, it was suspected that the rams' single horns were the product of art rather than nature, and in 1911 this was confirmed by the Prime Minister of Nepal, Maharaja Sir Chandra Shrim Shere Jang.
Answering a query made by a British resident in Nepal, the Prime Minister reported that unicorns were artificially created by ram herders, to be sold as curiosities:
"There is no special breed of one-horned sheep in Nepal, nor are the specimens which have been brought here for sale natural freaks. By certain maltreatment, which is described below, ordinary two-horned sheep are converted into a one-horned variety. The process adopted is branding with a red-hot iron the male lambs when about two or three months old on their horns when they are beginning to sprout. The wounds are treated with a mixture of oil and soot, and when they heal the horns, instead of growing at their usual places and spreading, come out as one from the middle of the skull ... "
1930s: Dr. Dove's Unicorn Experiments
Dr. William Franklin Dove, a biologist at the University of Maine, was familiar with the story of the unicorn rams of Nepal but skeptical about the method reported as having been used to craft their single horns. To prove his own theories, he developed a simple surgical procedure akin to a skin graft, to be humanely performed under local anesthetic.
Dr. Dove was aware that horns do not actually grow from the skulls of animals, but rather are initially attached to the skin of the scalp as "buds" which take root in the skull during the first weeks or months of the animal's life. By moving the un-anchored horn buds and trimming them so that they fit together, each presenting a flattened surface to the other, Dove was able to produce single-horned rams, goats and, most famously, a unicorn bull:
Dove reported that his unicorn bull became the leader of its herd and was very rarely challenged by other bulls, which is not surprising, going by the newsreel footage above; a 1500 lb. quadruped with a foot-long spike growing straight out of its head would be a fearsome enemy indeed. Dove also noted that the unicorn bull was seen to employ its unique horn as a tool - lifting fences, etc. - and that it was normally of a notably placid temperament.
1980s: NeoPagan Unicorns
Some older io9 readers may recall the most recent spate of "real unicorn" media reports. During the late 1970s, a colorful pair of neo-Pagans named (at that time) Otter and Morning Glory G'Zell became inspired by Peter S. Beagle's fantasy novel The Last Unicorn. When the G'Zells later came across Dr. Dove's research reports, they adopted his methods, cultivating a group of male unicorn goats.
Distinct from the mercenary intent of the Nepalese ram-herders or Dr. Dove's purely scientific interest in horn-bud transplantation, the G'Zells were primarily mystics and students of mythology. They theorized that, since many of the medieval representations of mythological unicorns resembled goats more than horses, the transplant process may actually have been part of a lost art of "experimental zoology". If so, its purpose might have been to create "supergoats"; male goats of generally placid temperament but more capable of defending themselves and their herds from predators than were most normal, two-horned goats.
During the early 1980s, the G'Zells exhibited their unicorn goats at Renaissance Faires, science fiction conventions and similar counter-cultural festivals. They might have slipped entirely under the mainstream media radar if not for their decision to lease four of their goats to the Ringling Brothers and Barnum and Bailey Circus.
As a publicity angle, the circus promoters made much of their new unicorns' "mysterious origins", which proved to be both an irresistible target for journalists and a magnet for public controversy.
Many third parties assumed that the unicorns' horns were either completely artificial fakes or that someone had cruelly transplanted cows' horns onto the heads of goats. Meanwhile, the G'Zells' contractual agreement with the circus did not allow them to comment publicly on the unicorns at all, so when they were inevitably tracked down by journalists, they were unable to offer much in the way of defense or explanation.
The circus management initially insisted that their unicorns were exactly as advertised, noting that "unicorn" simply means "single-horned". Under sustained media pressure, they eventually explained something about the unicorning process - including the detail that anesthetic was used and that the young goats suffered no more than some mild and temporary discomfort - and the controversy eventually died away.
This interview with Otter G'Zell (who now goes by the name Oberon Zell Ravenheart) includes an extensive memoir of his days as a creator of "living unicorns". Also, check out the Past Tense Kinja blog for more history of the weird and wonderful.