Shiki

Kinjishi the "Flying Pirate" is a currently unseen individual in the world of One Piece. His name, Kinjishi (金獅子), means "golden lion".

20 years ago, Kinjishi was the first, and so far the only, prisoner to escape from Impel Down due to a mistake made by the marines. It is unknown whether he was the sole escapee or if he lead a mass breakout.

Also worthy of note is that in the preview of the 10th One Piece movie scheduled to be released in December 2009, mention is made several times of a character in the movie bearing the exact same name, as well as supposedly being missing for twenty years, the approximate time of the Impel Down's escapee. If any relation will be made canon is yet to be seen.