Roll is Mega Man's "sister" and Dr. Light's third robot, after Mega Man and Proto Man. She is a housekeeping robot designed to assist Dr. Light, much like all the other robots he made. She is named "Roll" to match Mega Man's original name, which is "Rock", thus making the pun of "Rock and Roll".
First appearing in a cameo in Mega Man, she rarely plays a large role in the series, but she has been playable in Mega Man Powered Up, where she uses a broom (or a variation of it depending on the costume used) and has her own storyline. Other than that, she has been in Mega Man 8 and Mega Man 9 as a character that sells items to Mega Man in exchange for screws.
In spin-off Mega Man titles, she has played a big part in Super Adventure Rockman as the warning of the energy field, which kills all electronics, meaning she passed out first. She was first due to the fact she was a female. She was then worked on by Dr. Light, hoping one day she would return. If players get a game over, they see Roll in the bed followed by her dropping her hand, meaning she died. Dr. Light and Mega Man hug one another as Dr. Wily viciously cackles watching them suffer a loss on his TV. However, if the player gets to the end, the energy field gets wrecked and Roll comes back alive again, ending the game and bringing Earth to harmony.
She has been playable in both Marvel vs. Capcom: Clash of the Super Heroes and Marvel vs. Capcom 2: New Age of Heroes. She is usually counted as the "joke character" as her attacks are generally weak. She is also in Tatsunoko vs. Capcom in her Powered Up form, without the small body proportions. She fights with household cleaning tools like brooms.
In Street Fighter X Tekken, the downloadable character Mega Man, who appears in the game as a parody based on his appearance in the North American box art of the original NES game, is working under the orders of Roll, who likewise appears in a parody form. In Mega Man's arcade mode prologue, she appears as a beautiful adult woman who orders Mega Man to retrieve Pandora's Box from Antarctica.