Nanny Nightmare is a minor antagonist of the reboot TV series, Ben 10. He first appeared in the episode, Growing Pains.
In the mall, many people turned into babies because of Nanny Nightmare. She Kidnapped Ban and Gwen and turned them into toddlers. Ben transformed into Four Arms and he is also a toddler. They both went up and saw the machine that will turn everybody into babies. Ben transformed into upgrade, who is also a toddler and he upgraded the machine and reversed it. All babies are back to adults and Nanny Nightmare and her henchmen turned back to elderly.
She appeared as a woman with orange stripy dress, black apron, make up and blue hair, but when she become old, her hair is grey.
She is an egotistic type and she wanted to turn everybody into babies, so that she could rule.