The answer is Greenland, whose capital is Nuuk.
Greenland
Depends which one you mean. Three out of five of them are. Victoria Island, Nigeria definitely is. Ditto Victoria Island, Chile and Victoria Island in California. Google Earth shows Victoria Island in the Russian Arctic is well within (i.e. north of) the Arctic Circle. That leaves Victoria Island, Canada, which I'm guessing is the one that prompted the question. No, it is not south of the Arctic Circle. In fact, Victoria Island, Canada is entirely within (i.e. north of) the Arctic Circle, the largest island in the world with this distinction (and ninth largest island in the world, period).
The Arctic Circle runs right through Greenland.
The land on the Arctic Circle is divided among eight countries: Norway, Sweden, Finland, Russia, the United States (Alaska), Canada, Denmark (Greenland), and Iceland (where it passes through the small offshore island of Grímsey).
Baffin Island
No.
Iceland
iceland
Greenland
The majority of Canadian Islands located north of the arctic circle are in Nunavut. They are Ellesmere Island, Banks Island, Baffin Island and Victoria Island.
The Arctic Circle runs through Greenland.
Ellesmere Island