In Norse mythology, a vǫrðr (pl. verðir — "warden," "watcher" or "caretaker") is a warden spirit, believed to follow from birth to death the soul (hugr) of every person. In Old Swedish, the corresponding word is varþer; in modern Swedish vård, and the belief in them remained strong in Scandinavian folklore up until the last centuries. The English word '"wraith" is derived from vǫrðr, while "ward" and "warden" are cognates.
At times, the warden could reveal itself as a small light or as the shape (hamr) of the person. The perception of another person's warden could cause a physical sensation such as an itching hand or nose, as a foreboding or an apparition. The warden could arrive before the actual person, which someone endowed with fine senses might perceive. The warden of a dead person could also become a revenant, haunting particular spots or individuals. In this case, the revenant warden was always distinct from more conscious undeads, such as the draugar.
Under the influence of Christianity, the belief in wardens changed, and became more akin to the Christian concept of a good and a bad conscience.
A very old tree (often a linden, ash or elm) growing on the farm lot could be dubbed a "warden tree" (Swedish vårdträd), and was believed to defend it from bad luck. Breaking a leaf or twig from the warden tree was considered a serious offence. The respect for the tree was so great that the family housing it could adopt a surname related to it, such as Linnæus, Lindelius and Almén. It was often believed that the wights (Swedish vättar) of the yard lived under the roots of the warden tree, and to them, one sacrificed treats to be freed from disease or bad luck.