The Dread Pirate Roberts reference article from the English Wikipedia on 24-Apr-2004
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Dread Pirate Roberts

The Dread Pirate Roberts was a fictional pirate in the novel and movie, The Princess Bride.

The only thing known to the outside world concerning the Dread Pirate Roberts was that he never left captives alive. Presumably, then, his profound reputation was established solely by tales from former sailors on his ship, the Revenge.

Warning: Plot details follow.

Roberts actually was a series of different men. Approximately every five years, the current holder of the name chose a member of his crew to bestow the name upon. Everyone except the lucky pirate was released at a convienent port, a new crew was hired, and the former Roberts stayed aboard as first mate. The constant reference to "Captain Roberts" established the new Roberts' persona. After the crew was convinced, the former Roberts departed the ship, retrieved five years' worth of plunder, and retired in splendor.

The entire system worked, as Wesley relates to his love Buttercup, because Roberts operated entirely on fear. Ships would immediately surrender and send over their wealth rather than be captured by the Dread Pirate Roberts; but no one would surrender to the Dread Pirate Wesley.

Holders of the title Dread Pirate Roberts included: