After spending some time in Wayne Manor, Harriet eventually stumbled upon the secret elevator that connected the main house with the Batcave. She became suspicious of Bruce and Dick being Batman and Robin, and she tried to prove her theory by blocking the exits of the Batcave and placing a recording camera in the elevator. However, Bruce and Dick found a way to tamper with Harriet's plans and she was made believe that Batman and Robin were friends of Bruce and Dick.
When Alfred returned to Wayne Manor, Harriet assumed that she was supposed to leave, but Bruce, Dick and Alfred asked her to stay until Alfred was fully recovered.
Some time later, Aunt Harriet became very ill and she needed an urgent cryosurgery, but unfortunately, the Gotham City Hospital did not have the necessary equipment. For this reason, Batman and Robin took the cryothermal gun from Mister Freeze, as they stopped the villain and delivered the weapon to the hospital. Due to their timely help, Aunt Harriet could be saved and Mr. Freeze was captured.
When Dick moved out of Wayne Manor for College, Aunt Harriet returned to her own home, since Bruce and Alfred relocated to the Wayne Foundation penthouse and she had no longer any reason to remain there. At the penthouse her position as housekeeper was taken up by Caterina Valance, who only did the work part time and was not a live in domestic servant as Harriet had been.
- Julius Schwartz came up with the idea and the name of Aunt Harriet, inspired by Hoagy Carmichael's song Rockin' Chair, which talks about some "Aunt Harriet". The decision to include Aunt Harriet as a replacement for Alfred in the Batman comics, was to allay the claims made by Fredric Wertham that three single men living in a household seemed "suspicious". Aunt Harriet was included as a female companion for Batman and Robin, without having the heroes involved in silly romances as they previously had with Batwoman and Bat-Girl.
- When first introduced (and for several years afterward), she was always called Aunt Harriet and no last name was given. Her last name Cooper was first used in the comics in Detective Comics #373, several years after it was established on the Batman TV series.
- This version of Aunt Harriet, including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- It was never explained why Harriet Cooper did not take custody of Dick Grayson after his parents' deaths.
- 28 Appearances of Harriet Cooper (Earth-One)
- 1 Images featuring Harriet Cooper (Earth-One)
- Quotations by or about Harriet Cooper (Earth-One)
- Character Gallery: Harriet Cooper (Earth-One)