Herensuge

Herensuge, meaning dragon in euskera, is a mythical creature from primeval times sparingly making appearances across all of Basque Mythology.

Biography
Herensuge is less of an individual and more along the lines of multiple incarnations of the same character or species, all of them dying at the hands of a different hero every time.

Appearance and Personality
His appearance varies but is mostly depicted as an average to large-sized seven-headed flying serpentine-like dragon that terrorizes kingdoms and kills people for pleasure or hunger. He's consistently depicted as being very sadistic, kidnapping random people only to drown them, not even eating their bodies afterward.

Powers and Abilities
Though in some stories Herensuge is depicted as being so weak a man armed with a stick and a dog can kill it, in others it can kill horses, spit deadly fire and drive people mad at will. It's often described as being enormous (and with that comes great strength) and is usually depicted as being half-colubrid, meaning it possesses a venomous bite.

Trivia

 * Herensuge is possibly one of the most popular european dragons, likely moreso after its cameo in the anime Miss Kobayashi's Dragon Maid.