Greasy Greta is a large, middle-aged woman with black dotted eyes, shoulder-length hair and wearing a dress.
Little is known about Greasy Greta's personality, but of what could be seen in the chapter, she was a flamboyant and rude woman who would just eat the junk food from the kids without warning.
In the chapter "Horrid Henry and the Demon Dinner Lady", Greta was just doing her food-patrolling job , and even ate Henry's crisps he took with as packed lunch, and told the kids in the canteen that unhealthy food was not allowed in school. A day later, when she took Henry's chili powder-ridden biscuits and ate all of them, her mouth burned, and she ate Rude Ralph's doughnuts which made her case worse by choking, and finally drink a glass of water and running away from the canteen, never to be seen ever again.
- It is unknown if Greta came back to continue her food-patrolling job or not.