Karlsborg (, outdatedly ) is a locality and the seat of Karlsborg Municipality, Västra Götaland County, Sweden. It had 3,551 inhabitants in 2010. This garrisontown lies at the shore of lake Vättern in Västergötland.
The town of Karlsborg was established and grew due to the construction of Karlsborg Fortress, during the 19th century. According to the principles of a central defense, the fortress was designated as the reserve capital of Sweden in the event of war.
