Hannah is the mouse character who only appeared in the television series of Watership Down.
Prior to moving to Watership Down with Kehaar, she lived in Nuthanger Farm with the farmer's dog, Duster and cat, Tabitha. In the second episode of the series, she was used as bait to lure a troublesome weasel into a rock tunnel, since the escape hole in the burrow was small enough for her. Hannah lived on Watership Down with the rabbits afterwards, and became one of the supporting main characters in the series. She is notably one of the only characters who has the ability to use magic and plans to use it to save Watership Down, even though it will cost her her life, or at least her youth, but ultimately she does not have to as Silverweed sacrifices himself in her place.
Although she is not in the original story, Hannah still establishes her place as a character in the Watership Down television series. Despite her size Hannah is gutsy, feisty, spirited, adventurous and not afraid of creatures bigger than her. Even when cornered in bread box by Tabitha, she quickly shrugs off the peril she is in and decides to eat the bread and worry about the cat later. Hannah is courageous enough to go right into Efrafa itself to look for Campion, even though they have had no previous interaction. She is compassionate, which is shown by her willingness to help Kehaar and her disgust at the way General Woundwort rules his warren. Kehaar describes her as "nice but confusing" due to her advice that if one cannot find a home, they should make a home where they are. He also says that she has a "big spirit" which makes up for her small size. Hannah's strong will is shown by her strong resistance to Silverweed's mind reading abilities although eventually Silverweed manages to break through her defenses.
Hannah is very loyal to her friends and is not afraid of putting herself in danger in order to help them. She is even willing to die in order to protect them and would have done so, or at least aged to the point where she would be near death, had Silverweed not taken her place. She is especially close to Kehaar who often lets her ride on his back. Her close bond with Kehaar is created at Nuthanger Farm and strengthened by the fact that they are essentially the "outsiders" in the Watership Down warren due to the fact that neither of them are rabbits. After Kehaar leaves, Hannah misses him the most but finds a new flying friend in Skree although she is slow to trust him because he is a hawk.
Much like Blackberry, Hannah is a feminist saying "what's so special about bucks that they don't dig". She is very cheerful, has a good sense of humour and is also quite mischievous. She enjoys playing tricks as shown when she helps to trick Woundwort into thinking that Vervain has gone mad. Hannah also likes to tease her friends and at times her sense of humour can be somewhat sarcastic as she deliberately humiliates Bigwig by forcing him to apologize to her right in front of all the other rabbits, even though she has already forgiven him.
Although she is normally cheerful and friendly, Hannah also has a short temper and Kehaar claims that she is scary when she's angry. She sometimes jumps to conclusions, accusing Silverweed of being a traitor when he tries to stop her from using magic, thinking that he is trying to protect Woundwort, although he is actually trying to protect her. Hannah dislikes Bigwig's bossy attitude towards his Owsla as well has his tendency to belittle her because of her size. Kehaar describes their relationship as "always snarly warly". However they are friends and Bigwig shows great concern about her wellbeing when she is blown off Kehaar's back in a storm, even risking attracting Elil in order to find her. Hannah shows how much she cares about Bigwig by throwing herself onto an owl's back in order to protect him. She then scolds him for breaking his own rules by being noisy and attracting the owl's attention in the first place. Bigwig later tells her that he is proud to be her friend and that "size isn't a measure of courage".
Hannah can use her size to her advantage as it allows her to get through spaces that rabbits cannot, which proves vital to defeating a weasel and allows her to spy on the Efrafan's while they are interrogating Campion. While she cannot fight on the ground, Hannah is good at throwing acorns and uses this in combination with Kehaar's flying skills to attack opponents.
Hannah does not talk about her past and it is never revealed how she recieved the wound in her right ear, although it was most likely caused by Tabitha.