Thunder was a Rabbit from Efrafa. He took part in the Seige of Watership down. He was only mentioned a few times. He was not an Owsla of Efrafa, however he did have experience in seigeing warrens, so Woundwort relied on his advice and made him do some errands when they were digging out the Watership Down Warren. What happened to him after the Dog attack is unknown.