Horgr is a type of altar, constructed of piled stones, used by the Vikings in religious and civil ceremonies.

A typical use of the horgr would be to place upon it a bowl of the blood of an animal sacrificed to a Norse deity (e.g. a goat for Thor, a sow for Freya, a boar for Freyr), then dipping a bundle of fir twigs into it and waving the bundle in the form of the "hammer-sign" to spatter the participants with the blood. This would consecrate the attendees to the ceremony, such as a wedding.