There is a patent
on a method of growing real, live unicorns
The process involves surgical alteration of a one-week old goat, arranging its' horn buds so that they grow together. The patent claims that said unicorn would be ideal for use as a guard animal, as it would have higher general intelligence and physical attributes (as compared to what, exactly, is unclear). The US Patent Office awarded patent US4429685 to Timothy G. Zell in 1984.
For more information on the HISTORY of this technique (pre-patent) see Living Unicorn Project (thanks to Wuukiee for pointing this out).