The red squirrel (Sciurus vulgaris) is a species of tree squirrel in the genus Sciurus common throughout Europe and Asia. The red squirrel is an arboreal, primarily herbivorous rodent.

In Great Britain, Ireland, and in Italy numbers have decreased drastically in recent years.This decline is associated with the introduction by humans of the eastern grey squirrel (Sciurus carolinensis) from North America. However, the population in Scotland is stabilising due to conservation efforts, awareness and the increasing population of the pine marten, a European predator that selectively controls grey squirrels.