Berserker pendant

 Berserker Pendants were talismans created by Berserkers which gave the bearer the ability to order people to do as they wished. A Pendant would also slowly changed the person using it into a Berserker. Each time it was used, the Pendant would slightly change the bearer both physically and mentally until the bearer desired to complete the transformation into a Berserker. During transformation the user develops prominent veins over the skin's surface. The final form has the appearance of a man wearing animal skins. The only cure, if done early enough, is to remind the affected person who they are so that the memories will reassert their identity.

According to UNIT archives, a Berserker Pendant surfaced in a barracks in Ealing in 1940, but was lost during a German bombing raid. This same Pendant was rediscovered by Jacob West, who used it for a time until it frightened him. He gave it to Rani Chandra, who placed it in Sarah Jane Smith's attic. It was then discovered by Paul Langer, who stole it and used it to take control of his son Clyde. Mr Langer was almost completely possessed by the power of the Pendant until his wife and son reminded him of who he really was. Clyde then used to Pendant to erase his mother's memories of the incident, then disposed of it in the sea. (SJA: The Mark of the Berserker)