Speedwell was a rabbit who originated from Sandleford Warren. He left the Warren with Hazel, Fiver, Pipkin, Bigwig, Hawkbit, Dandelion, Blackberry, Silver, Acorn, and Buckthorn, to start their own warren which eventually came to be known as The Watership Down Warren. He was very good friends with Acorn.
When first introduced he, along with Acorn, were described as “thin-looking six monthers, with the strained, wary look of those only too well used to the thin end of the stick“. At one time he wanted to go back to the Sandleford Warren along with Hawkbit and Acorn, but he was forced to continue on by Bigwig.
Speedwell is subsequently characterized as an energetic, easy-going joker who later makes a loyal and hard-working contribution to the defense of the warren against General Woundwort. He is also the narrator of one of the short stories in Tales from Watership Down (book), the nonsense tale Speedwell's Story.
He appeared in Watership Down (book) and Tales from Watership Down (book). However, he has not appeared in any of the adaptations. However, it is possible that in the film, he was among the many rabbits to come with Hazel and Fiver, but he didn't make it past the Owsla, and in turn, was suffocated along with the other remaining rabbits, when the warren was filled in by humans.