Nelson Mandela was a historic figure, no less. But even in his "greatness", there are some acts in his life that diminish his stature in my eyes, even as I mentioned somewhere else that he was released from prison the day I turned 22 (which of course is trivial and does not add to anything, heh).
I will not link to anything since these are readily available in the web: he had many women in his life, did not renounce violence (contributory to many deaths and a little too friendly with dictators), and signed South Africa's abortion law that is one of the worst this world has seen (without restrictions that even allowed non-doctors to perform), among others.