Royal family of the Principality of Monaco. The Grimaldi family has been in power, on-and-off, for over 700 years. The current crown prince is HSH Prince Rainier III, with the heir apparent being HRH Prince Albert. Monaco's Laws of Sucession are classified as being "male primogeniture", meaning that male descendants of the monarch are placed before their sisters, but any of the monarch's children, regardless of gender, get precedence over the siblings of the current monarch.

Family Tree:
                               Otto Canella
                           (d. before Jun 1143)
                             Consul of Genova
                                     |
                             Grimaldo Canella
                             (known 1162-1184)
                                     |
                              Oberto Grimaldi
                                 (d. 1252)
                                     |
                           +---------+---------+---------+--------+
                           |                   |         |        |
                   Grimaldo Grimaldi          Ingo     Oberto  Nicolas
                      (1210-1257)         (1210-1235)
                           |
               +-----------+---------+
               |           |         |
            Luchetto    Antoine  Lanfranco
          House of the   (1259)  (d. 1293)
        Counts of Beuil              |
                                 Rainier I
                             (known 1267-1314)
                              Lord of Cagnes
                             Admiral to France
                                     |
                                 Charles I
                                 (d. 1341)
                              Lord of Monaco
                                     |
                                Rainier II
                                (1350-1407)
                              Lord of Monaco
                                     |
         +------------+--------------+
         |            |              |
     Ambroise      Antoine         Jean I
    (1419-1427)  (1419-1427)    (1382-1454)
    Co-Lord of   Co-Lord of   Lord of Monaco
      Monaco       Monaco            |
                                  Catalan
                                 (d. 1457)
                              Lord of Monaco
                                     |
                                  Claudine--married--Lambert Grimaldi
                                (1451-1515)    |        (1420-1494)
                                               |
                   +-----------------+---------+------+
                   |                 |                |
           Jean II of Monaco     Lucien I         Augustin
              (1468-1505)       (1487-1523)       (d. 1532)
                              Lord of Monaco   Lord of Monaco
                                     |        Bishop of Grasse
                                Honore I
                                (1522-1581)
                              Lord of Monaco
                                     |
                     +---------------+-------------+------------+
                     |               |             |            |
                  Charles         Hercule      François      Horace
                (1555-1598)     (1562-1604)   (1557-1586)  (1558-1559)
              Lord of Monaco  Lord of Monaco
                                     |
                                 Honore II
                                (1597-1622)
                           Prince of Monaco 1612
                                     |
                                  Hercule
                                (1623-1651)
                                Never Ruled
                              Marquis des Baux
                                     |
                                  Louis I
                                (1642-1701)
                                     |
                                 Antoine I
                                (1661-1731)
                                     |
                            +--------+--------+
                            |                 |
                     Antione Charles  Louise-Hippolyte----married-----Jacques de Goyon
                      (illegitimate)     (1697-1731)         |           de Matignon
                       (1697-1784)                           |           (1731-1733)
                   The Grimaldi Knight                       |        Prince of Monaco
                                                             |          via marriage
                                                         Honore III
                                                        (1720-1795)
                                                     Prince of Monaco
                                                             |
                                           +-----------------+
                                           |                 |
                                       Honore IV       Florestan I
                                      (1758-1819)       (1785-1856)
                                   Prince of Monaco  Prince of Monaco
                                                             |
                                                        Charles III
                                                        (1818-1889)
                                                     Prince of Monaco
                                                             |
                                                          Albert I
                                                        (1848-1922)
                                                     Prince of Monaco
                                                             |
                                                          Louis II
                                                        (1870-1949)
                                                     Prince of Monaco
                                                             |
                                                         Charlotte------married---Pierre de Polignac
                                                        (1989-1977)        |        (1895-1964)
                                                                           |
                                                                      Rainier III
                                                                    (b. 31 May 1923)
                                                                     Prince in 1949
                                                                        married
                                                                      Grace Kelly
                                                                           |
                                 +---------------------------------+-------+------------------+
                                 |                                 |                          |
                             Caroline                            Albert                   Stéphanie
                         (b. 23 Jan 1957)                   (b. 14 Mar 1958)           (b. 1 Feb 1965)
                                 |                          Marquis des Baux                  |
                                 |                                                            |
       +-----------------+---------------+-----------------+                +-----------------+---------------+
       |                 |               |                 |                |                 |               |
    Pierre            Andréa         Charlotte         Alexandra          Louis            Pauline         Camille
(b. 5 Sep 1987)  (b. 8 Jun 1984)  (b. 3 Aug 1986)  (b. 20 Jul 1999)  (b. 26 Nov 1992)  (b. 4 May 1994)  (b. Jul 1998)
                                                 Princess of Hannover

Credit to: http://www.monte-carlo.mc/us/presentation/history/arbregene.html, http://genealogy.euweb.cz/grim/grimaldi3.html, http://www.riviera-magazine.com/tourisme/monaco/MonacoHist-us.html, Tiefling's Laws of Succession node