Ms. Grunion is one of the three secondary villains in animated television horror film Scooby-Doo: Unknown Assailant. She is voiced by Allison Janney, who is also voiced Peach the Starfire in Finding Nemo and Finding Dory and Gladys Sharp in Over the Hedge.
Little is known of Ms. Grunion before her first encountered with Fauntleroy Donaldson, but it is known that she was a leader of a group of bikers, and two of her members were William Harangue (John DiMaggio) and Rojo (Jennifer Hale).
Ms. Grunion, along with William Harangue, and Rojo stops at a convenience store in Ponyville. Both Ms. Grunion and William Harangue held Thunder Lane (Trevor Devall) hostage, while Rojo was making trouble for Rainbow Dash (Ashleigh Ball). When she has Thunder Lane's thrown black wallet, she wants Rainbow Dash to ask her very politely for the purple wallet back with a word "Red", so Rainbow Dash does. Both Ms. Grunion and William Harangue let Thunder Lane go. While he and Rainbow Dash get ready to leave, Ms. Grunion was outside in front of the store drinking a can of chrysanthemum tea as she Thunder Lane and Rainbow Dash inside the car. When Thunder Lane starts the car, Ms. Grunion begins smashing the windshield of a car that Thunder Lane was driving. However, Thunder Lane runs over their motorcycles as revenge for troubling him and Rainbow Dash, causing Ms. Grunion to fume and shout in anger while Rainbow Dash praises Thunder Lane as they drive away.
The three bikers stops at the Sweet Apple Acres. Ms. Grunion goes to a barn across from Applejack's house and discovers William Harangue dead. When she sees Fauntleroy Donaldson, she grabs a meat cleaver. Fauntleroy continues his scope out of the barn, only to have Ms. Grunion appear and starts attacking him with a meat cleaver. Fauntleroy counterattacks by hitting Ms. Grunion with a baseball bat. While Fauntleroy is trying to kill Rarity (Tabitha St. Germain), she runs into the barn. She's suddenly met by Ms. Grunion, who survived the earlier fight. Enraged, Fauntleroy turns his attention to Ms. Grunion by using a meat cleaver to chops off her left hand. Rarity continues running in fear as Ms. Grunion screams in horror after Fauntleroy chops off her left hand and hacked her to death with his meat cleaver. Ms. Grunion's one-handed corpse was later found by the authorities and taken away by the paramedics.