The Throat Wolf is perhaps the most famous hoax related to Magic: The Gathering. It was the legend of a non-existent card. In many variations of the story, the Throat Wolf was an extremely rare card, usually a creature card described as having 'double first strike' or 'firstest strike'. Various versions continue to circulate on the internet, usually with obscure or technically impossible rules text.
Stories about the card began in May 1994 when usenet poster Jesse Fuchs added a reference to the card in a follow-up to a trade notice . Over the next couple of weeks, Fuchs and other posters on rec.games.deckmaster began discussing the made-up card as if it were real. Fuchs even posted a "rules question" to the group describing the card as being able to attack during the opponents turn . This was perhaps the turning point of the hoax, since many Usenet readers posted follow-ups discussing the card - apparently unaware that it did not exist.
These first posts were made during a time when Legends had just been released. Since this was before the ubiquity of the Internet, many players didn't have access to full card lists and spoiler lists, and so had no way of knowing whether this card was real or not. In fact, Legends was plagued with card distribution problems and many cards at the time really were "ultra-rare". As time passed, the Throat Wolf legend spread and grew.
Later, the term was used in a variety of in-jokes, and Magic R&D often used it as a temporary name for a card in development. The Homelands card named Heart Wolf pays homage to the hoax. The Visions card Talruum Champion was originally designed for Mirage using the playtest name 'Throat Wolf' -- its ability is essentially "firstest strike".
In an article in the Duelist #9, Throat Wolf was described as 5 colorless mana for a 4/4 Summon Throat Wolf. The abilities read, "Firstest Strike. Throat Wolf may attack during your opponent's untap phase. Attacking does not cause Throat Wolf to tap." The flavor text read "The most feared of Dominia's mythical creatures, the Throat Wolf is wylie and unpredictable. Its incredible speed and attack abilities have prompted many net.wizards to wonder if it is real. Ask the Throat Wolf, he'll tell you....
In the short story Chef's Surprise by Sonia Orin Lyris in the Magic: The Gathering anthology Distant Planes, the main character, Asmoranomardicadaistinaculdacar, works as a chef for the demon Vincent, Lord of the Pit. All of the meals she cooks for him are actual cards from the game (for example, atog pâté on honey-soaked ironroot bark; Atog and Ironroot Treefolk are both creature cards) except one: Barbequed Throat Wolf ribs.