Viper

Vipers were a type of predatory, venomous snake. The Fourth Doctor suggested that one of the Seven Holy Rituals of the Swampies by which he was to die would be to hang upside down over a pit of vipers. (TV: The Power of Kroll ^[+]Loading...["The Power of Kroll (TV story)"])

A viper was used in one of the deadly tricks played on the Second Doctor, John and Gillian Who by the Jokers. (COMIC: The Jokers ^[+]Loading...["The Jokers (comic story)"])