Short answers, pulled from the story.
Frederick II was King of Denmark and Norway and Duke of Schleswig and Holstein from 1559 until his death on the 4th of April 1588. Born on the 1st of July 1534 at Haderslevhus Castle, he was a member of the House of Oldenburg and the father of Anne of Denmark and Christian IV.
The negative portrait of Frederick II was largely founded by the cultural historian Troels Frederik Lund in his 1906 biography of Peder Oxe, which cast Frederick as a reckless king saved by his treasurer. Frederick's heavy dyslexia made him appear unlettered to his contemporaries, and later historians focused on his struggles with drink and his love of hunting. Archival research by Frede P. Jensen (1940-2008) and Paul Douglas Lockhart reversed this assessment, concluding he was enlightened as few monarchs of his generation were.
Frederick II rebuilt Kronborg at Elsinore from a medieval fortress into a Renaissance castle between 1574 and 1585, commissioning 43 tapestries for its Great Hall from Dutch craftsmen in Helsingør. He also converted Hillerødsholm into Frederikborg Castle in 1560, fortified Skanderborg Castle in 1561, founded Fredrikstad in Norway in 1567, and established Denmark's first national road network, the kongevej or King's Road.
Frederick II granted Tycho Brahe the island of Ven as a fief in 1576, where Brahe built the observatory Uraniborg. From 1576 until his expulsion in 1597, Brahe supervised the first publicly funded scientific research institute in European history. Frederick personally selected Ven as the site and told Brahe it was his duty as king to support such work.
The Northern Seven Years' War was a conflict between Denmark-Norway and Sweden fought from 1563 to 1570, ending in the status quo Treaty of Stettin. It cost Denmark-Norway approximately 1.1 million rigsdaler. Frederick II led his army personally on the battlefield and at one point drafted a letter of resignation when the Council of the Realm cut off tax funding, though the Council's fear of an interregnum brought him back.
Sophie of Mecklenburg-Güstrow, whom Frederick married on the 20th of July 1572, was his first half-cousin and a descendant of King John of Denmark. Their marriage is regarded as among the most harmonious royal unions in Renaissance Europe; Frederick's handwritten diary consistently calls her "mynt Soffye," meaning "my Sophie." The couple had seven children in the first ten years of their marriage, including Anne of Denmark and Christian IV.