Nebuchadnezzar.
In Daniel 4, King Nebuchadnezzar has a vision, which Daniel
interprets for him. Daniel tells Nebuchadnezzar that he will be
driven from men, and that he will dwell with the beasts of the
field, and eat grass like oxen, for seven years, until such time
that he comes to realize that "the Most High rules in the kingdom
of men, and gives it to whomever he chooses." (NKJV). Daniel
advises Nebuchadnezzar to turn from his wicked ways, and show mercy
to the poor.
Instead, about one year later, Nebuchadnezzar is admiring all
that he has, and boasts "Is not this great Babylon, that I have
built for a royal dwelling by my mighty power and for the honor of
my majesty?" (NKJV). That very hour the vision of Nebuchadnezzar
began to be fulfilled - Nebuchadnezzar was driven from men and ate
grass like oxen for 7 years. At the end of those 7 years,
Nebuchadnezzar lifted his eyes to heaven, and his understanding
returned to him. He blessed the Most High and praised and honored
Him. Nebuchadnezzar's kingdom was then restored to him.
Medical experts tell us that this could have been a case of
Clinical Lycanthropy, a rare psychiatric syndrome in which an
individual believes s/he is or has become an animal; or that it
could have been due to a severe syphilis infection that resulted in
paralytic dementia.