The cover of "Don't Stay Up Late"
Brenda Hart is the main villainess of "Don't Stay Up Late", the second book in R.L. Stine's revived Fear Street series (published on April 7, 2015).
She was the "mother" of Harry Hart and the sister of Alice Hart. She was also the old friend of therapist Dr. Shein. Due to returning to work, Brenda hired teenager Lisa Brooks to babysit for Harry. She initially treated Lisa with kindness, but she harbored a dark secret: Harry was a demonic creature, and Brenda had plotted with Alice and Dr. Shein to create him, having previously failed to do so three times in the past. Also aiding their twisted plan were Lisa's boyfriend Nate Goodman and her best friend Saralynn O'Brien. To prevent Harry from escaping the house and attacking people, Brenda strongly instructed Lisa not to let Harry stay up late. But Harry was able to trick Lisa into thinking he went to bed on time while he secretly stayed up late, attacking and killing two of Lisa's classmates. It is later revealed that she had originally had teenager Joy Fergus babysit Harry, but had Dr. Shein institutionalize the girl after she discovered her secret.
Brenda's villainous reveal came after Harry transformed into his monstrous form in front of her, her having let him stay up late after much begging. Brenda arrived soon after and became angry at Lisa, blaming her for the deaths her son caused. She then told Lisa that she couldn't allow her to leave due to her knowing too much before attacking Lisa with a knife, intending to kill her. Suddenly, Nate burst in through the front window and hit Harry over the head with a lamp to subdue him. The enraged Brenda tried to attack Nate, but he managed to restrain her, allowing Lisa to escape. Brenda (along with Alice) disappeared after that and Harry reappeared at a daycare Lisa began working at, but her official fate is left unknown.