The House of Habsburg (or "of Austria", as it was known to contemporaries) descended from Charles I of Spain (who was also the Holy Roman Emperor Charles V). He left behind a Spanish monarchy that also, for some time, retained control of the Netherlands; however, the title of Holy Roman Emperor did not pass to these Spanish monarchs.

Charles I of Spain: 23 January 1516 – 16 January 1556
Philip II: 16 January 1556 – 13 September 1598, 1580 Portugal was joined to the union
(Philip II was also King of Chile from 1554 to 1556)

Philip III: 13 September 1598 – 31 March 1621
Philip IV: 31 March 1621 – 17 September 1665, in 1640 Portugal became independent once more
Charles II: 17 September 1665 – 1 November 1700[1]

House of Bourbon
The Spanish kings of the House of Bourbon were descended in male line from the French royal family.

Philip V: 16 November 1700 – 14 January 1724
Louis I: 14 January – 31 August 1724[2]
Philip V (restored): 6 September 1724 – 9 July 1746
Ferdinand VI: 9 July 1746 – 10 August 1759
Charles III: 10 August 1759 – 14 December 1788
Charles IV: 14 December 1788 – 19 March 1808
Ferdinand VII: 19 March – 6 May 1808[3]
Charles IV (restored): 6 May 1808[4]

House of Bonaparte

Joseph I Napoleon (king of the Spain and the Indias, by divine grace): 6 June 1808 – 11 December 1813[5]

House of Bourbon (first restoration)
See also House of Bourbon.

Ferdinand VII (again: king of Castile, Leon, Aragon,... by divine grace): 11 December 1813 – 29 September 1833
Isabella II: 29 September 1833 – 30 September 1868[6]

House of Savoy

Amadeo I (king of Spain, by divine grace and will of nation): 2 January 1871 – 11 February 1873

Interregnum: First Republic
First Spanish Republic: 1873 – 1874

House of Bourbon (second restoration)

Alfonso XII (constitutional king of Spain): 29 December 1874 – 25 November 1885[7]
Alfonso XIII: 17 May 1886 – 14 April 1931

Interregnum: Second Republic and Franco era
Second Spanish Republic: 1931 – 1939
Generalissimo Francisco Franco: In parts of the country from 1 October 1936 and in its entirely from 1 April 1939 until his death on 20 November 1975[8]

House of Bourbon (third restoration)

Juan Carlos I (king of Spain): 22 November 1975 –

Sources :

- Ernie Richards, Plus Ultra Newsletter, several editions.

-Wikipedia