A wyvern (or wivern) is a winged reptilian legendary creature often found in medieval heraldry. It is similar to a European dragon, but it differs in that it has only two legs, cannot breathe fire, and has a barbed or snake-like tail. Occasionally, it is said to be smaller than a dragon or to be able to breathe fire. In heraldry, it represents pestilence, conquest, or other such ideas.
Another mythical creature that is similar to the wyvern is the cockatrice. Variants of the wyvern include the sea-wyvern, which has a fish-like tail, and the Lindworm, which either has no legs (commonly) or no wings.