Blackbeard the pirate, or Edward Teach, has often been confused with Bluebeard-often unintentionally, but sometimes intentionally by writers who link the the actual pirate with the character. In a time when most men were clean-shaven, both men terrified listeners with their odd beards-Blackbeard's grew all over his face, and he would even light slow-burning fuse cords under his hat so that his beard would appear to be burning and smoke would rise out of it.
Visitors to the U.S. Virgin Islands can visit either Blackbeard's Castle, said to have been used by Blackbeard and now a U.S. National Historic Landmark:
Or, on the other side of town, Bluebeard's Castle, a resort. It was supposedly built by Bluebeard for his love, Mericedita, who cheated on him, so he left her.
Aside from the pirate, other serial killers have been referred to in the press as Bluebeards, such as H.H. Holmes, who married bigamously and was convicted of killing 27 men, women, and children. His "murder castle," specifically designed with "labyrinthine corridors, chutes to the cellar, a vault disguised as a room, trapdoors, and dead ends" was referred to as "Bluebeard's Chamber of Horror." Henri Landru, Johann Otto Hoch, George Joseph Smith, and Ed Gein are other murderers with similar enough details to merit comparison.
Bluebeards are not limited to males-female serial kills of husbands (mostly for monetary gain) are also referred to as Lady Bluebeards, such as Belle Gunness and Lyda Trueblood.
Information was taken from the book Bluebeard: a Reader's Guide to the English Tradition by Casie E. Hermansson. This book was one of my Christmas presents...nothing like a nice morbid post to start off the new year, right?