Here is a list of national leaders: http://en.wikipedia.org/wiki/List_of_national_leaders
Does any of the men there have long hair?
I believe the previous prime minister of Japan had somewhat long hair (was superseded in September).
I have been going through them one by one, but a lot of them have no picture. Prime Minister Feleti Sevele of Tonga has slightly longish hair. That's the longest I've found so far.
...and then there's Libyan dictator Muammar al Gaddafi
... and Dr Abdul Kalam, President of India
The Indian President seems to have the longest hair. It's long enough that most people would call it long, but I think most of us here would regard it more like mid length.