Beavers were animals in the family Castoridae. (PROSE: Wetworld [+]Loading...["Wetworld (novel)"]) The were well known for building dams. (PROSE: Parasite [+]Loading...["Parasite (novel)"])
When the Doctor's TARDIS landed inside the Squirrel Club Clubhouse, the Fifteenth Doctor inexplicably turned into a beaver, a form that a slightly bewildered Doctor cited as being "new". (TV: The Doctor's TARDIS lands in iconic BBC shows [+]Loading...["The Doctor's TARDIS lands in iconic BBC shows (TV story)"])
Caius Roose's species looked like a humanoid beaver. (PROSE: Picnic at Asgard [+]Loading...["Picnic at Asgard (short story)"])
Sundayan otters resembled otters but had incisors like beavers. (PROSE: Wetworld [+]Loading...["Wetworld (novel)"]) Lavellans also resembled beavers and otters. (PROSE: Predating the Predators [+]Loading...["Predating the Predators (short story)"])