Rocs

Though possibly only a fabrication of myth and rumor-mongers, the Roc is said to be unbelievably huge - big enough to swoop down and carry off animals as large as horses. They are said to dwell high in the mountains, which may account for why no one has ever encountered one and lived to speak of it.

One can only hope these gargantuan birds -- if they ever even existed -- died off in the First Age of Darkness with the death of the evil wizard Mondain.

Trivia
Although pictured in the first Apple II manual for the original Ultima I release, the Roc remains an unconfirmed creature in the game. Why would the illustration be included if it never made it into the actual game?