Big Blizzard Bear

The Big Blizzard Bear is a special bear mount awarded for attendants of BlizzCon 2008. It comes with a baby murloc who holds a BlizzCon flag.

Source
This item comes from the BlizzCon 2008 Welcome package. It was also obtainable via DirectTV subscription in the USA and Main Event in Australia. The mount must first be unlocked using a code found on the Blizzard Convention Card.

Zas'Tysh at Valley of Honor in Orgrimmar redeems it for Horde players, while Ransin Donner at Forlorn Cavern in Ironforge for Alliance players.

Having this mount awards the Feat of Strength Big Blizzard Bear (achievement).

Mount Journal
Whenever you ride this mount, you feel the urge to shout, "Cry havoc and let slip the murlocs of war!"

Trivia

 * This was the first mount that was "Bound to account".