Which country has a unicorn as its national animal?

Scotland picked the unicorn, and picked it precisely because of who was standing opposite. In medieval heraldry the unicorn was the proud, untameable beast, and the lion was the king of animals and the emblem of England. Choosing the one creature said to be the lion's natural enemy was a political statement as much as a decorative one. The unicorn appeared on Scottish royal arms from the 1300s and was formalised by James III in the fifteenth century. When James VI of Scotland became James I of England in 1603, the two animals were placed on the same coat of arms, and they still stand there together. The Scottish unicorn is always shown in chains, usually read as a symbol of a dangerous power held under control.

The unicorn is chained on the Scottish arms and free on the version used in England.