Fantomas/WMG

There are quit a few theories attempting to link Fantomas and his extended family to other literary characters.

Fantomas and Juve are twin sons of Rocambole

 * Rocambole was the protagonist of a series of crime thriller novels, which lasted from 1857 to 1870. Rocambole started out as a villain, "a ruthless, brilliant schemer, motivated purely by greed. He steals and murders without remorse, but with a wicked sense of humor and banter". Then he redeemed himself, using his skills as a vigilante crime-fighter. Though always evading the law. His early death left two sons orphan. Two orphans that would inherit different sides of Rocambole's personality.
 * Their mother was apparently Miss Ellen Palmure (Palmer?), who served as both Rocambole's opponent and love interest in The Miseries Of London (1867-1868). Hélène is named after her paternal grandmother.

Fatala is a member of Fantomas' line.

 * Fatala was a Femme Fatale villain protagonist of another series created by Marcel Allain. She was active in 1930s. The theory goes that she was a daughter of Hélène, modeling herself after the explois of her mother and maternal grandfather.

Fantomette is a member of Fantomas' line.

 * Fantomette/Françoise Dupont was a Kid Hero, protagonist of a series of novel which started in 1961. 51 volumes had appeared by 2009, and more may eventually appear. The theory goes that she chose the codename to lay claim to the mantle of her ancestor Fantomas. But has more in common with Inspector Juve than most members of her line. While having similar skills to Hélène and Fatala.

Satanas is a member of Fantomas' line.

 * Satanas was a villain created by Gabriel Bernard, first appearing in 1922. His methods consisted of spreading fear and chaos, exactly like Fantomas. The theory is that Satanas was not merely a Captain Ersatz of Fantomas, but actually modelled himself after him. And that he was another family member laying claim to the mantle, possibly a grandson.
 * Jean-Marc Lofficier has suggested Satanas as a good mate for Belphegor/Simone Desroches, the main villainess in the 1928 film of that name. A figure who dresses as a ghosdt to strike fear to the heart of her enemies.

Diabolik is a member of Fantomas' line.

 * Diabolik first appeared in 1962, and also had the Master of Disguise abilities and ruthlessness of Fantomas. The theory is that the "orphan" actually is another scion of the same family.