Gustav II Adolf
This statue may look a bit boring, but it depicts a important person in swedish history. More interesting though is the place where it stands...
But lets begin by telling who the fellow on the horseback is!
Gustav II Adolf was the king of Sweden from 1611 until 1632 when he died at the battle at Lützen, Germany, during the thirtyyear war.
You can read more about him (in english) at Wikipedia.
He stands at the Gustav II Adolf square which is the "zero point" in Stockholm. All distances to Stockholm itself are measured from this square which, even if it is quite anonymous, makes it a very interesting place and point.