The human brain is the most complex of all that is currently known in the universe.  We have barely begun to understand how and why it works the way it does.  Mental Illness describes those who suffer from the way their brain functions. Society does not understand this complex dynamic, therefore the "mentally ill" are stigmatized. However, we forget that this variation in function often comes with gifts of higher mental capacity.  Without the contribution of these exceptional thinkers, the world would be a very different place.  Here are some of the more famous:

Mark Linkous | Depression

Michael Blosil (Marie Osmond's son) | Depression

Andrew Koenig | Depression

Alexander (Lee) McQueen: Designer - Depression

Abraham Lincoln: President - Depression

Nikola Tesla: Inventor - Obsessive-Compulsive Disorder