What it is
The Eurasian beaver is a large nocturnal rodent that dams streams and fells trees. IUCN lists it as Least Concern after a long collapse and a managed recovery. It is a different species from the North American beaver (Castor canadensis).
Range
Once from Britain to China along rivers and wetlands. By the early twentieth century only a few thousand survived in scattered European and Asian pockets. Reintroductions have restored it to much of Europe.
What happened
Fur, castoreum, and meat drove a hunt that nearly ended the species in Europe. Legal protection and releases from the mid-twentieth century onward rebuilt numbers. The early Holocene beaver was an engineer of ice-free rivers; the beaver of today is often a reintroduction on a drained landscape.
When / status
Still here, and increasing in Europe after a near miss.
Human role
Overhunting for fur almost finished it; later policy put it back.
Sources
IUCN Red List (Castor fiber, Least Concern); European reintroduction summaries.