Denmark was a country on the continent of Europe on Earth. The Danes were one of the peoples who comprised the seafarers known as Vikings. Denmark's flag was red with a white Nordic cross. (ENT: "First Flight")
Hamlet was a 7th century Danish king, whose murder was avenged by his like-named son. This story became the famous tragedy by Shakespeare. (TOS: "The Conscience of the King")
In the 16th century the Danish king supported the astronomical research of his subject Tycho Brahe. Captain Archer told an anecdote about Brahe as a diversion when captive on the Vulcan monastery planet. (ENT: "The Andorian Incident")
In the late 20th century, Denmark was a founding member of the European Space Agency. (ENT: "First Flight")
Commander Chakotay recalled that the epic poem Beowulf was set in 6th century Denmark. (VOY: "Heroes and Demons")