- ❝ I got the brain cancer. ❞
- — Grandma Quinzel
Grandma Quinzel is the grandmother of Harley Quinn. She seen in the sitcom-parody sequence having a stable relationship with her husband but they began to grown in disdain for one another throughout the years and eventually had fully developed a sense hatred for each other. When Harley arrived at her parents' house, Grandma Quinzel revealed she had been diagnozed with brain cancer but soon after she died by being shot through the back of her head by a sniper attempting to kill Harley's father for unpaid money he owed to the mob.
Grandma Quinzel has a presumably hateful relationship with her husband. She seemed to love Harley coming back home, noting that she may not have long left to live as she nonchalantly announces she has brain cancer.
Grandma Quinzel is seen wearing a pink blouse with a cream-white, long-sleeve coat over it. She wears black glasses with thick rims and a light blue tint in the lenses. She has grey hair worn in a bun on top of her head.
- Grandma Quinzel's appearance is based on the older The Animated Series version of Harley who appears at the end of Batman Beyond: Return of the Joker.