Olsker is a small community in the north of Bornholm island, Denmark.

[1] It is known for having the highest of the island's four round churches, Sankt Ols Kirke, from which it takes its name.

[2][3] Olsker also has Bornholm Cable substation.

It used to serve sailors as a landmark for navigation.

To the east of the church, evidence of bronze-age and iron-age settlements have been found as well as living quarters from the Viking period.