Rudolf II (18 July 1552 – 20 January 1612) was Holy Roman Emperor (1576–1612), King of Hungary and Croatia (as Rudolf I, 1572–1608), King of Bohemia (1575–1608/1611) and Archduke of Austria (1576–1608). He was a member of the House of Habsburg.
Rudolf's legacy has traditionally been viewed in three ways: an ineffectual ruler whose mistakes led directly to the Thirty Years' War; a great and influential patron of Northern Mannerist art; and an intellectual devotee of occult arts and learning which helped seed what would be called the scientific revolution.
Rudolf was born in Vienna on 18 July 1552. He was the eldest son and successor of Maximilian II, Holy Roman Emperor, King of Bohemia, and King of Hungary and Croatia; his mother was Maria of Spain, a daughter of Charles V and Isabella of Portugal. He was the elder brother of Matthias who was to succeed him as king of Bohemia and Holy Roman Emperor.
Rudolf spent eight formative years, from age 11 to 19 (1563–1571), in Spain, at the court of his maternal uncle Philip II. After his return to Vienna, his father was concerned about Rudolf's aloof and stiff manner, typical of the more conservative Spanish court, rather than the more relaxed and open Austrian court; but his Spanish mother saw in him courtliness and refinement. Rudolf would remain for the rest of his life reserved, secretive, and largely a homebody who did not like to travel or even partake in the daily affairs of state. He was more intrigued by occult learning such as astrology and alchemy, which was mainstream in the Renaissance period, and had a wide variety of personal hobbies such as horses, clocks, collecting rarities, and being a patron of the arts. He suffered from periodic bouts of "melancholy" (depression), which was common in the Habsburg line. These became worse with age, and were manifested by a withdrawal from the world and its affairs into his private interests.
Like his near contemporary, Elizabeth I of England (who was born 19 years before he was), Rudolf dangled himself as a prize in a string of diplomatic negotiations for marriages, but never in fact married. During his periods of self-imposed isolation, Rudolf reportedly had affairs with his court chamberlain, Wolfgang von Rumpf, and a series of valets. One of these, Philip Lang, ruled him for years and was hated by those seeking favour with the emperor.
In addition, Rudolf was known to have had a succession of affairs with women, some of whom claimed to have been impregnated by him.
Many artworks commissioned by Rudolf are unusually erotic.
Historians have traditionally blamed Rudolf's preoccupation with the arts, occult sciences, and other personal interests as the reason for the political disasters of his reign.
Although raised in his uncle's Catholic court in Spain, Rudolf was tolerant of Protestantism and other religions including Judaism. He largely withdrew from Catholic observances, even in death denying last sacramental rites. He had little attachment to Protestants either, except as counter-weight to papal policies. He put his primary support behind conciliarists, irenicists and humanists. When the papacy instigated the Counter-Reformation, using agents sent to his court, Rudolf backed those who he thought were the most neutral in the debate, not taking a side or trying to effect restraint, thus leading to political chaos and threatening to provoke civil war.
His conflict with the Ottoman Empire was the final cause of his undoing. Unwilling to compromise with the Turks, and stubbornly determined that he could unify all of Christendom with a new Crusade, he started a long and indecisive war with the Turks in 1593. This war lasted till 1606, and was known as "The Long War". By 1604 his Hungarian subjects were exhausted by the war and revolted, led by Stephen Bocskay (Bocskai Uprising). In 1605 Rudolf was forced by his other family members to cede control of Hungarian affairs to his younger brother Archduke Matthias. Matthias by 1606 forged a difficult peace with the Hungarian rebels (Peace of Vienna) and the Turks (Peace of Zsitvatorok). Rudolf was angry with his brother's concessions, which he saw as giving away too much in order to further Matthias' hold on power. So Rudolf prepared to start a new war with the Turks. But Matthias rallied support from the disaffected Hungarians and forced Rudolf to cede the crowns of Hungary, Austria, and Moravia to him. At the same time, seeing a moment of royal weakness, Bohemian Protestants demanded greater religious liberty, which Rudolf granted in the Letter of Majesty in 1609. The Bohemians continued to press for further freedoms, and Rudolf used his army to repress them. The Bohemian Protestants then appealed to Matthias for help; Matthias' army then held Rudolf prisoner in his castle in Prague, until 1611, when Rudolf ceded the crown of Bohemia to his brother.
Rudolf died in 1612, nine months after he had been stripped of all effective power by his younger brother, except the empty title of Holy Roman Emperor, to which Matthias was elected five months later.
Patron of arts, collector of curiosities
Rudolf moved the Habsburg capital from Vienna to Prague in 1583.
Rudolf's love of collecting went far beyond paintings and sculptures.
He patronized natural philosophers such as the botanist Charles de l'Ecluse, and the astronomers Tycho Brahe and Johannes Kepler both attended his court. Tycho Brahe developed the Rudolphine Tables (finished by Kepler, after Brahe's death), the first comprehensive table of data of the movements of the planets. As mentioned before, Rudolf also attracted some of the best scientific instrument makers of the time, such as Jost Bürgi, Erasmus Habermel and Hans Christoph Schissler. They had direct contact with the court astronomers and, through the financial support of the court, they were economically independent to develop scientific instruments and manufacturing techniques.
Rudolf kept a menagerie of exotic animals, botanical gardens, and Europe's most extensive "cabinet of curiosities" (Kunstkammer) incorporating "the three kingdoms of nature and the works of man". It was housed at Prague Castle, where between 1587 and 1605 he built the northern wing to house his growing collections. A lion and a tiger were allowed to roam the castle, documented by the account books which record compensation paid to survivors of attacks, or to family members of victims.
Rudolf was even alleged by one person to have owned the Voynich manuscript, a codex whose author and purpose, as well as the language and script and posited cipher remain unidentified to this day. According to hearsay passed on in a letter written by Johannes Marcus Marci in 1665, Rudolf was said to have acquired the manuscript at some unspecified time for 600 gold ducats. No evidence in support of this single piece of hearsay has ever been discovered. The Codex Gigas was also in his possessions.
As was typical of the time, Rudolf II had a portrait painted in the studio of the renowned Alonso Sanchez Coello.
By 1597, the collection occupied three rooms of the incomplete northern wing.
Rudolf's Kunstkammer was not a typical "cabinet of curiosities" – a haphazard collection of unrelated specimens.
As was customary at the time, the collection was private, but friends of the Emperor, artists, and professional scholars were allowed to study it. The collection became an invaluable research tool during the flowering of 17th-century European philosophy, the "Age of Reason".
Rudolf's successors did not appreciate the collection and the Kunstkammer gradually fell into disarray.
Astrology and alchemy were regarded as mainstream scientific fields in Renaissance Prague, and Rudolf was a firm devotee of both. His lifelong quest was to find the Philosopher's Stone and Rudolf spared no expense in bringing Europe's best alchemists to court, such as Edward Kelley and John Dee. Rudolf even performed his own experiments in a private alchemy laboratory. When Rudolf was a prince, Nostradamus prepared a horoscope which was dedicated to him as 'Prince and King'. In the 1590s Sendivogius was active at Rudolph's court. 
Rudolf is also the ruler in many of the legends of the Golem of Prague, either because of, or simply adding to, his occult reputation.
- History of Austria
- Kings of Germany family tree; he was related to every other king of Germany
- Moldavian Magnate Wars for the background on southern wars (with Ottoman Turkey and its allies)
- Vespasiano I Gonzaga, a friend of Rudolf who built a Renaissance "Ideal city" in Sabbioneta, Italy
- Mineral collecting – Rudolf II was 16th century most famous mineral collector whose collections were curated by Anselmus Boetius de Boodt