You're fishing for "Antarctica", although small portions of
that continent extend north of the Antarctic Circle.
Antarctica
Wherever the Antarctic Circle crosses land, the land is part of the continent of Antarctica.
The continent of Antarctica is crossed by and surrounded by the Antarctic Circle.
There are no countries in this geography, only a continent: Antarctica. There are no countries on the Antarctic continent.
The answer you want is Antarctica.
Antarctica
Antarctica is the most southerly continent on Earth, located almost entirely within the Antarctic Circle. It is known for its extreme cold temperatures and vast icy landscapes.
The Antarctic Circle surrounds Antarctica.
The two continents that do not extend into the tropics are Antarctica and Europe. Only Europe Antarctica is considered a geographic region, not a continent, by geographers.
Antarctica is the only continent that the Antarctic Circle passes through.
The continent of Antarctica.
Australia and Antarctica suit your question.