Madame Hydra

Ophelia Sarkissian was orphaned by war, raised by Hydra, and rose to run it. As Madame Hydra and later as Viper she has led the organisation, run the Serpent Society, ruled the criminal city-state of Madripoor and poisoned more people than the rest of Marvel's villain roster combined. Green hair, a snake motif, and a genuine belief that the world would be improved by a controlled extinction event.

Her strangest chapter is also her most famous: to settle a debt with the Silver Samurai, she blackmailed Wolverine into marrying her, making Viper legally Logan's wife for a considerable stretch of continuity. It is the kind of detail that explains why she has survived five decades without ever being Marvel's top-tier villain: she is too odd to retire and too specific to replace.

Jim Steranko created Madame Hydra in Captain America #110 in 1969, at the peak of his run on the character, and she immediately became one of Hydra's most recognisable leaders. She later took the Viper name, absorbing the identity of an earlier Serpent Squad villain.

Her career runs through Captain America, Wolverine, X-Men and Daredevil titles: leading the Serpent Society, ruling Madripoor, and infamously blackmailing Wolverine into marriage during his 1990s run. She has held the title of Supreme Hydra multiple times, usually while planning to poison everyone including her own organisation.