score:9
If we are only counting modern history - rather than ancient Greece or the like - the Netherlands was the first country to recognize same-sex marriage in 2001, and their head of state is (and was) Queen Beatrix.
Upvote:4
Not exactly a SSM but very, very close: in Denmark "civil union" or "registered partnership" was allowed in 1989 - see wikipedia:
A civil union, also referred to as a civil partnership, is a legally recognized form of partnership similar to marriage. Beginning with Denmark in 1989, civil unions under one name or another have been established by law in many developed countries in order to provide same-sex couples rights, benefits, and responsibilities similar (in some countries, identical) to opposite-sex civil marriage.
In Denmark, there are still some differences between an ordinary marriage and registered partnership, e.g. in regard to adoption and in heritage...
UPDATE: Today - 2012-06-07 - we have actually adopted a new law that will fully allow SSM and not just registered partnerships. [L106 in Danish]
Upvote:8
Iceland prime minister Jóhanna Sigurðardóttir had joined in a civil union with Jónína Leósdóttir in 2002, and had converted the union to the marriage in 2010 as soon as that became legal in Iceland. It is logical to suppose she supported gay marriage at least since 2002 though of course she wasn't the prime minister then.
Spain's Zapatero declared he supports gay marriage as soon as he became Primer Minister in 2004.