Uncle and Niece
Uncle and Niece is in Married Relationships.
In 142BC or 141BC Ptolemy VIII Physcon 184BC 116BC (43) and Cleopatra III 160BC 101BC (18) were married. They were uncle and niece.
In 1424 Prince John Aviz Constable Portugal 1400-1442 (23) and Isabella of Braganza 1402-1466 (21) were married. They were uncle and niece. He a great grandson of King Edward III England. 
In 1475 Alfonso "The African" V King Portugal 1432-1481 (42) and Joanna "La Beltraneja" Trastámara Queen Consort Portugal 1462-1530 (12) were married. They were uncle and niece. He a great x 2 grandson of King Edward III England. She a great x 3 granddaughter of King Edward III England. She by marriage Queen Consort Portugal.
In 1484 Giacomo or Jacques Savoy Count Romont 1450-1486 (33) and Marie Luxemburg Countess Vendôme and Soissons -1547 were married. They were uncle and niece. He a great x 5 grandson of Edward "Longshanks" I King England 1239-1307. She a great x 4 granddaughter of King Edward III England. 
In 1570 Philip "The Prudent" II King Spain 1527-1598 (42) and Anna of Austria Queen Consort Spain 1549-1580 (20) were married. They were uncle and niece. He a great x 5 grandson of King Edward III England. She by marriage Queen Consort Spain.
Before 09 Jul 1578 Charles Habsburg Spain II Archduke Austria 1540-1590 (38) and Maria Anna Wittelsbach 1551-1608 (27) were married. They were uncle and niece. He a great x 5 grandson of King Edward III England. 
On 14 May 1582 Ferdinand Habsburg Spain II Archduke Austria 1529-1595 (52) and Anna Caterina Gonzaga Archduchess Austria 1566-1621 (16) were married. They were uncle and niece. He a great x 5 grandson of King Edward III England. She by marriage Archduke Austria.
On 15 Jul 1635 Maximilian "The Great" Wittelsbach I Duke Bavaria I Elector Bavaria 1573-1651 (62) and Maria Anna Habsburg Spain Duchess Bavaria 1610-1665 (25) were married. They were uncle and niece. She by marriage Duchess Bavaria.
Before 1651 Philip IV King Spain 1605-1665 and Mariana of Austria Queen Consort Spain 1634-1696 were married. They were uncle and niece. She by marriage Queen Consort Spain.
On 27 Sep 1755 Augustus Ferdinand Hohenzollern 1730-1813 (25) and Princess Elisabeth Louise Hohenzollern 1738-1820 (17) were married. They were uncle and niece. He a grandson of George I King Great Britain and Ireland 1660-1727. She a great granddaughter of George I King Great Britain and Ireland 1660-1727.
Before 1800 John Acton 6th Baronet 1736-1811 and Mary-Ann Acton Lady Acton 1782-1873 were married. They were uncle and niece. She by marriage Lady Acton of Aldenham Hall.
On 11 Jul 1824 Jacob "James" Mayer de Rothschild 1792-1868 (32) and Betty von Rothschild 1805-1886 (19) were married. They were uncle and niece.
In 1829 Ferdinand VII King Spain 1784-1833 (44) and Maria Christina of the Two Sicilies Queen Consort Spain 1806-1878 (22) were married. They were uncle and niece. He a great x 5 grandson of Charles I King England Scotland and Ireland 1600-1649. She by marriage Queen Consort Spain.
On 23 Dec 1832 Ernest Saxe Coburg Gotha I Duke Saxe Coburg Gotha 1784-1844 (48) and Marie Württemberg Duchess Saxe Coburg Gotha 1799-1860 (33) were married. They were uncle and niece. She by marriage Duchess Saxe Coburg Gotha.
On 24 Feb 1837 Benjamin Lee Guiness 1st Baronet Guiness 1798-1868 (38) and Elizabeth Guiness 1813-1865 (23) were married. They were uncle and niece.
Benedetto Maria Maurizio Savoy 1741-1808 and Maria Anna Savoy Duchess Chablais 1757-1824 were married. They were uncle and niece. He a great x 2 grandson of Charles I King England Scotland and Ireland 1600-1649. She a great x 3 granddaughter of Charles I King England Scotland and Ireland 1600-1649.
Cadwaladr ap Gruffudd Aberffraw 1100-1172 and Tangwystl ferch Cadwallon were married. They were uncle and niece.
John Cocks of Castleditch in Eastnor in Herefordshire and Mary Cocks were married. They were uncle and niece.