The line of succession to the British Throne (and, by extension, the thrones of the fifteen other commonwealth realms) is determined by male primogeniture, whereby the eldest son of the incumbent inherits the throne. The line of succession then follows the descendants of the person in line before going on to consider their siblings. Sons are always considered before daughters, but daughters are included in the succession. See Succession to the British Throne for further details.
Line of succession
Anyone who is a Roman Catholic or who marries one is excluded from the throne under the Act of Settlement 1701. For the earlier part of the list (through Crown Prince Alexander of Yugoslavia) they have been noted below as "skipped", but after that all descendants of Electress Sophia have been listed.
HRH Princess Helen of Romania , Mrs. McAteer, daughter of King Michael
Nicholas Medforth-Mills , son of Princess Helen
Karina Medforth-Mills , daughter of Princess Helen
HRH Princess Irina of Romania , Mrs. Kreuger, daughter of King Michael
Michael Kreuger , son of Princess Irina
Angelica Kreuger , daughter of Princess Irina
Sophie de Laufenborg , daughter of King Michael
Elisabeta-Maria de Laufenborg , daughter of Princess Sophie
HRH Prince Peter of Yugoslavia , great-great-great-great-grandson of Queen Victoria through Prince Alfred (skipped his father Crown Prince Alexander of Yugoslavia)
HRH Prince Philip of Yugoslavia , son of Crown Prince Alexander
HRH Prince Michael of Yugoslavia , brother of Prince Nikolas
HRH Princess Katarina of Yugoslavia , sister of Prince Nikolas
Victoria de Silva , daughter of Princess Katarina
HRH Prince Karl Wladimir of Yugoslavia , great-great-great-grandson of Queen Victoria through Prince Alfred
HRH Prince Dimitri of Yugoslavia , brother of Prince Karl Wladimir
HRH Princess Maria Tatiana of Yugoslavia , Mrs. Thune-Larsen, sister of Prince Karl Wladimir
Sonja Thune-Larsen , daughter of Princess Tatiana
Olga Thune-Larsen , daughter of Princess Tatiana
Ileana Snyder , great-great-great-granddaughter of Queen Victoria, through Alfred, Queen Marie of Romania, and Princess Ileana of Romania, skipping a number of her Catholic relations.
Nicholas Snyder , son of Ileana Snyder
Alexandra Snyder , daughter of Ileana Snyder
Constanza Snyder , daughter of Ileana Snyder
HIH Grand Duchess Maria Vladimirovna of Russia , great-great-granddaughter of Queen Victoria through Prince Alfred
HIH Grand Duke George Mikhailovitch of Russia , son of Grand Duchess Maria Vladimirovna
HSH Princess Cécilia of Leiningen , great-great-great-great-granddaughter of Queen Victoria through Prince Alfred (skipped her father Prince Karl Emich of Leiningen )
HSH Princess Theresa of Leiningen , daughter of Prince Karl Emich
HSH Prince Andreas of Leiningen , brother of Prince Karl Emich
HSH Prince Ferdinand of Leiningen , son of Prince Andreas
HSH Prince Hermann of Leiningen , son of Prince Andreas
HSH Princess Olga of Leiningen , daughter of Prince Andreas
HSH Princess Melita of Leiningen , sister of Prince Karl Emich
HSH Princess Stephanie of Leiningen , sister of Prince Karl Emich
HSH Prince Boris of Leiningen , great-great-great-grandson of Queen Victoria through Prince Alfred
HSH Prince Nicholas of Leiningen , son of Prince Boris
HSH Prince Hermann of Leiningen , brother of Prince Boris
HSH Princess Tatiana of Leiningen , daughter of Prince Hermann
HSH Princess Nadia of Leiningen , daughter of Prince Hermann
HSH Princess Alexandra of Leiningen , daughter of Prince Hermann
HSH Princess Kira of Leiningen , great-great-granddaughter of Queen Victoria through Prince Alfred
HSH Princess Mechtild of Leiningen , great-great-granddaughter of Queen Victoria through Prince Alfred
Ulf Bauscher , son of Princess Mechtild
Berthold Bauscher , son of Princess Mechtild
Erik Bauscher , son of Berthold Bauscher
Franka Bauscher , daughter of Berthold Bauscher
Johann Bauscher , son of Princess Mechtild
HRH Prince Friedrich Wilhelm of Prussia , great-great-grandson of Victoria through Prince Alfred and his daughter Victoria Melita.
Prince Philipp of Prussia , son of Prince Friedrich Wilhelm
Prince Paul Wilhelm of Prussia , son of Prince Philipp
Princess Maria Luise of Prussia , daughter of Prince Philipp
Princess Elisabeth Christine of Prussia , daughter of Prince Philipp
Princess Anna Sophie of Prussia , daughter of Prince Philipp
Princess Johanna Amalie of Prussia , daughter of Prince Philipp
Prince Friedrich Wilhelm (the younger) of Prussia , son of Prince Friedrich Wilhelm the elder
Prince Joachim Albrecht of Prussia , son of Prince Friedrich Wilhelm the elder
Princess Viktoria Luise of Prussia , daughter of Prince Friedrich Wilhelm
HRH Prince Michael of Prussia , brother of Prince Friedrich Wilhelm the elder
Princess Micaela of Prussia , daughter of Prince Michael
Maximilian Wessuly , son of Princess Micaela
Princess Nataly of Prussia , daughter of Prince Michael
Due to the propensity of British monarchs to marry their cousins, it is often the case that the consorts of monarchs are also in the line of succession.
HM Queen Mary, consort of George V was also on the line of succession despite the fact she was a Queen consort. She was the great-granddaughter of George III through her mother. As such she could have succeeded the throne as Queen regnant. This would be unlikely given her low position during her lifetime.