Which is the only country that is also an entire continent?

Australia qualifies as both country and continent because it's the only recognized full continent also governed as a single sovereign nation, with no other countries sharing its territory. Other continents are divided among many nations, or in Antarctica's case governed by treaty with no permanent population, which is why Australia's situation is genuinely unique.

Greenland, despite its size, is politically part of Denmark and geographically grouped with North America, not its own continent; Antarctica is unambiguously a continent but not a country, since it has no permanent residents or government.

Australia's isolation as a single-nation continent shaped its unusual wildlife dramatically, since animals evolved for millions of years with little outside competition, producing marsupials found nowhere else.