Doorknobder is a Daimon Heart Snatcher sent by Eugeal to help her steal Pure Hearts. She was created from a doorknob by Doctor Tomoe. She has the power to create doors and walls to seal exits, but is not a good fighter, and is a bit of a coward. She appeared in Sailor Moon S Episode 20, No Turning Back.
Eugeal took Doorknobder with her as she extracted Mina's Pure Heart. Doorknobder sealed the exits to trap Serena, Amara, and Michelle inside, forcing them to transform in front of each other. Doorknobder was reluctant to fight them, as she was not much of a fighter. After being attacked by Sailor Neptune, she begged Eugeal to make her stop fighting, but Sailor Moon shot a Moon Spiral Heart Attack at Eugeal, who kicked Doorknobder away and deflected the attack with her flamethrower, causing it to hit Doorknobder and destroy her.
Doorknobder is one of two Monsters of the Week to be destroyed when Sailor Moon was aiming for a major antagonist, the other being Cele Cele's servant, Togetoge.