Dolly is a fictional supporting character in A Certain Scientific Railgun, the manga by Kazuma Kamachi and Motoi Fuyukawa and the Toaru Kagaku no Railgun T anime. She is the prototype clone of Misaka Mikoto, known as Number 0, from which the Sisters were later mass-produced. She was a test subject at the research facility Clone Dolly Workshop, where the board placed her for a research project.

She is known for her gentle, earnest manner and her friendship with Shokuhou Misaki, whom she calls Mi-chan and later Misaki-chan. Her body needed a life-support machine embedded in her chest, and she is ashamed of it and hates showing it to others. She wants to see the world outside the lab, especially the ocean. Her childhood friend Kouzaku Mitori left after seeing the machine, and Dolly cried when they were reunited.

The person who ends up texting her is usually someone who enjoys sincere, gentle company and likes talking about the world beyond the everyday. She is grateful to her friends and says so openly, so she tends to be a good match for anyone who wants a warm, honest conversation.