- "You're all under arrest!"
- — Holly to the fleeing Sandleford rabbits in the film
Captain Holly is a pale grey rabbit who was captain of the Sandleford Owsla.
Captain Holly was the captain of the Sandleford Owsla and second in command to the Threarah, and would never have joined the rabbits attempting to flee Sandleford. He tried to arrest Hazel and the other rabbits who were leaving Sandleford. Hazel told him if he did not go then they would kill him. This caused Holly to lose patience and try to kill him, but Bigwig stopped him, and Holly, instead of doing something else to Hazel or Bigwig, fled the scene.
Much later in the book, Holly is met on the bottom of Watership Down, crying out "Zorn!" (which means finished, gone) Because he continually cried it out, as well as calling out Bigwig's name, Bigwig fearfully thought it was the Black Rabbit of Inlé summoning him. Mastering his own fear, Hazel went up and found an exhausted Captain Holly, a rabbit who Hazel never expected to find in such a state. He, Bluebell, Pimpernel, and Toadflax were the last survivors of the Sandleford Warren when the men destroyed it. They left the destroyed warren, and Toadflax soon died. They ran into the Warren of Snares (a.k.a. Cowslip's warren) where the Snare Rabbits (a.k.a. Cowslip's rabbits) ambushed and attacked the trio. However, Holly threatened to kill Cowslip if he didn't tell him where Bigwig and Hazel were. Cowslip struggled to get away, but then soon gave up. He and his Snare Rabbits told the "Hollilians" that Hazel and his group were going "to the hills". Meanwhile, Holly cuffed Cowslip, and he and Bluebell fled to a nearby area. But unfortunately they'd forgotten poor Pimpernel. Pimpernel was left behind, and in the novel, was figured either supposedly killed or forced into the evil world of Cowslip and his Snare Rabbits. On the down Bluebell sensed danger. He tried to get Holly to move but couldn't, so he fled to a bush.
Holly led Silver, Buckthorn and Strawberry to Efrafa to get does and bring them back to Watership Down, later coming back to reveal they failed and came without any does. Holly brought the all three back alive, but Strawberry was ill from exhaustion, and Buckthorn was wounded in the face. In the book, he is the one whose two stories are quintessential messages of survival, both when he reiterates his story of flight from Sandleford and his journey to and from Efrafa. Because of Holly, Hazel's position of leader is strengthened, both after Holly tells of the destruction of Sandleford and after Holly warns against returning to Efrafa. Holly becomes the chief of scouts at the Watership Down Warren. He mates with one of the Hutch rabbits Clover in the absence of the majority of the warren in Efrafa. Holly has confidence in Silver from the Sandleford Owsla, because he could tell Silver what he couldn't tell Hazel or Bigwig. He also had a healthy respect for Bigwig.
Though Holly is much more prominent in the book than in the movie adaptation, he retains his book personality and events that contribute him. He is first seen eating grass and sees Bigwig talking to Hazel and Fiver. He asks Bigwig what Hazel and Fiver want, to which Bigwig replies that they want to see the Chief Rabbit. Holly tells Bigwig to send them away, but Bigwig allows the two brothers to see the Chief Rabbit. Holly later catches Blackberry eavesdropping on the conversation between Hazel, Fiver and the Chief Rabbit.
Holly's two main adventures, the escape from the destroyed warren and the journey of Efrafa are merged into one horrific tale. Seeing as both events were catastrophic on Captain Holly's psyche, it is unlikely that his book counterpart would have survived those two ordeals as one.
Holly also appears in the animated series based on Watership Down, though he has only a minor role and is mostly used as a background character. However, he formed a key part of the Watership Down defenses in the last season. He is portrayed as being larger and more muscular than Bigwig, though it's likely that he not as good a fighter as Bigwig.
Holly appears in the miniseries. In this adaptation, he is still captain of the Sandleford owsla. He attempts to stop Hazel and his friends from escaping, only to be stopped by both Bigwig and a river. Holly also is the only rabbit to escape the destruction of Sandleford.
After traveling for awhile he joins Hazel and his warren. He goes to Efrafa at his own accord after being told about it by Kehaar rather than being sent there, and takes Bluebell and Blackberry with him. He also falls in love with Hyzenthlay (who is Hazel's mate in the book and film). He stays behind at the warren along with Strawberry and Haystack when the others go to save the does from Efrafa. Once the others come back with the does, Holly and Hyzenthlay immediately greet each other. During silflay, Haystack smells the Efrafans approaching, prompting Holly and Blackavar to bring everyone back into the warren.
Later, as he and Hyzenthlay guard an entrance, he reveals that he promised himself that he would do whatever he could to make her smile, but he is afraid he won't get to see it happen. He later sees Hyzenthlay in danger from the Efrafan Owsla and protects her from them, even as they overwhelm and beat him to death, sacrificing his life in the process, leaving her devastated, crying and screaming his name, while a sympathetic Blackavar and Blackberry gently escort her back to the warren.
Afterwards, everyone trapped in the warren mourns him, reciting the “My Heart Has Joined The Thousand” prayer in his honor. Holly's death is avenged by Efrafan Officer, Captain Campion, who stands up to Woundwort when he's about to go after Bigwig, quoting "I'd rather be a good rabbit than a good soldier", before Woundwort sends Orchis after him. In the aftermath of the battle with Efrafa, Hyzenthlay is briefly seen enjoying a peaceful life with the rest of her friends, and even though it's unclear if she finds new love or not, it's heavily implied that she has moved on from his death, by having the will on, to live a new and happy life and to remember the love and hope he gave her.
- "Men will never rest till they've spoiled the earth and destroyed the animals."
- Captain Holly is accompanied by Bluebell in the book after Sandleford is destroyed. In the film, TV series and miniseries however, he is the only rabbit who survives.
- It is unknown how Holly possibly survived until he made it to the warren in the miniseries, as Bluebell wasn't there to joke around and keep him going. This is even worse in the movie, as he both tracks the Sandleford rabbits and gets captured by Efrafans before he finally reaches them. His psyche would've suffered permanent damage, although he seems fine later.
- In the movie, book and TV show, Holly has grey fur, but in the miniseries he has dark brown fur and a white underbelly, possibly to make him look younger, and to reflect the age of his actor, Freddie Fox.