2nd, 10 years ago the passing of Countess Anne Dorte of Rosenborg, daughter-in-law of Hereditary Prince couple Knud and Caroline-Mathilde of Denmark
7th, 95th birthday of Countess Monique Boulay de la Meurthe, youngest daughter of Princess Isabelle of Orleans, Countess Bruno d´Harcourt
7th, 85th birthday of Prince Michel of Greece
17th, 75th birthday of Baron Christian Louis de Massy, first cousin to the Prince of Monaco
17th, 20th birthday of Farah Pahlavi, daughter of Reza Pahlavi, head of the House of Pahlavi (Iran)
21st, 20th birthday of Princess Ingrid Alexandra of Norway, granddaughter of the King
22nd, 70th birthday of Prince Peter zu Sayn-Wittgenstein-Sayn, brother of the present head
23rd, Silver wedding anniversary of Prince Ernst August of Hannover and Princess Caroline of Monaco (separated?)
24th, 100 years ago the wedding of Duke Albrecht Eugen of Württemberg and Princess Nadezhda of Bulgaria
24th, 100 years ago the birth of John Spencer, later 8th Earl Spencer and father of Princess Diana
26th, 100 years ago the wedding of Crown Prince Hirohito of Japan (later the Emperor Showa) and Princess Nagako Kuni, paternal grandparents to the present Emperor
February
3rd, 100 years ago the birth of Friedrich Wilhelm, Prince von Hohenzollern, father of the present head
5th, 80th birthday of Princess Clarissa of Hessen, first cousin of King Charles III of the United Kingdom
7th, 25 years anniversary on the throne of King Abdullah of Jordan
11th, 100 years ago the wedding of Prince Erik of Denmark and Lois Frances Booth
12th, 90th birthday of Caroline, Dowager Duchess of Fife, and mother to the present 4th Duke of Fife (a Queen Victoria descendant)
14th, 80th birthday of Anastasia, Fürstin consort zu Löwenstein-Wertheim-Rosenberg, second cousin of Queen Margrethe of Denmark
14th, 70th birthday of Richard Scott, 10th Duke of Buccleuch
14th, 100 years ago the birth of Patricia Mountbatten, later 2nd Countess Mountbatten of Burma
17th, 70th birthday of Princess Marie-Astrid, Archduchess Carl Christian of Austria
17th, 50th birthday of Al-Muhtadee Billah, Crown Prince of Brunei
18th, 40th birthday of Stéphanie, Hereditary Grand Duchess of Luxembourg
20th, 10th birthday of Princess Leonore of Sweden, grandchild of the Swedish King
21st, 200 years ago the passing of Eugène de Beauharnais, Duke of Leuchtenberg, father of Queen Josephine of Sweden and Norway
26th, 70th birthday of Prince Ernst August, Head of the house of Hanover
28th, 30th birthday of Eleonore von Habsburg-Lothringen, daughter of Karl von Habsburg, head of the house of Habsburg-Lorraine
29th, 60th birthday of James Ogilvy, son of Princess Alexandra of Kent
March
3rd, 40th birthday of Countess Caroline af Rosenborg, granddaughter of Prince Flemming of Denmark
6th, 85th birthday of Infanta Margarita of Spain, Duchess of Soria
6th, 70 years ago the passing of Charles Edward, Duke of Saxe-Coburg und Gotha
6th, 60 years ago the passing of King Paul of Greece
8th, 70th birthday of Nanasipauʻu Tukuʻaho, Queen consort of Tonga
10th, 60th birthday of Prince Edward, Duke of Edinburgh
11th, 100 years ago the passing of Duke Peter Alexandrovich of Oldenburg, first husband of Grand Duchess Olga Alexandrovna of Russia
11th, 60th birthday of Prince Karl Vladimir of Yugoslavia, first cousin of Crown Prince Alexander
12th/15th, 30th wedding anniversary of Felix & Barbara, Fürst and Fürstin zu Hohenlohe-Waldenburg-Schillingsfürst
14th, 30th birthday of Louis Spencer, Viscount Althorp, nephew of late Diana, Princess of Wales
15th, 40th birthday of Pss D.Amélia of Orléans-Bragança, Mrs Alexander Spearman
16th, 75th birthday of Hieronymus, Fürst von Colloredo-Mannsfeld
20th, 20 years ago the passing of Juliana, Queen of the Netherlands 1948-1980
22nd (April 20th), Diamond wedding anniversary of Hans Veit (son of Greek princess) & Henriette, Count and Countess zu Toerring-Jettenbach
23rd, 50th birthday of Princess Badiya bint Hassan, first cousin to the King of Jordan
26th, 75th birthday of Princess Margarita of Romania
31st, 30th birthday of Count Mauritz Douglas, grandson of Archduke Otto von Habsburg
April
5th, 70 years ago the passing of Crown Princess Märtha of Norway, mother of the present King
9th, 80th birthday of Countess Cecilia Bernadotte, granddaughter of Prince Wilhelm of Sweden and Grand Duchess Maria of Russia
10th, 50th birthday of Prince Hussain Aga Khan, son of Aga Khan IV
15th, 50 years ago the passing of Princess Irene, Duchess of Aosta
19th, 95th birthday of Lady Pamela Hicks, first cousin to late Prince Philip, Duke of Edinburgh
25th, 70th birthday of Prince Joao of Orleans-Braganza
26th, 80th birthday of Yasuko Konoe, former Princess Yasuko of Mikasa (Japan)
26th, 30 years ago the passing of Zein al-Sharaf, Queen consort of Jordan, paternal grandmother of the present King
27th, 80th birthday of Peregrine Cavendish, 12th Duke of Devonshire
28th, 60th birthday of Lady Helen Taylor, daughter of the Duke of Kent
28th, 30th birthday of Princess Rajwa Al Hussein, wife of the Crown Prince Hussein of Jordan
29th, 80th birthday of Princess Benedikte of Denmark, sister of the present Queen
29th, 60 years ago the wedding of Prince Carlos Hugo of Bourbon-Parma and Princess Irene of the Netherlands
30th, 85th birthday of Pieter van Vollenhoven, husband of Princess Margriet of the Netherlands
May
1st, 60th birthday of Lady Sarah Chatto, first cousin to King Charles III
3rd, 50th birthday of Princess Haya bint Hussein of Jordan, half-sister to the present King
4th, 100 years ago the birth of Prince Michael Feodorovich of Russia, grandson of Grand Duchess Xenia Alexandrovna of Russia (sister of the last tsar)
5th, 70th birthday of Erik Vind, grandson of Prince Erik of Denmark, later count of Rosenborg
6th, 70 years ago the passing of Cecilie, German Crown Princess
12th, 50th birthday of Prince Wenzeslaus of Liechtenstein, nephew of the present Prince
13th, 30th birthday of Heinrich-Donatus, Hereditary Prince zu Schaumburg-Lippe
14th, 20th wedding anniversary of Crown Prince Frederik and Crown Princess Mary of Denmark
19th, 70th birthday of Archduchess Maria-Anna of Austria, Princess Peter Galitzine
20th, 60th birthday of Charles Spencer, 9th Earl Spencer, brother of late Princess Diana
21st, 100 years ago the birth of Princess Marie Adelaide of Luxembourg, later Countess Karl Josef Henckel von Donnersmarck, paternal aunt to the present Grand duke of Luxembourg
22nd, 20th wedding anniversary of King Felipe and Queen Letizia of Spain
25th, 40th birthday of Prince George of Yugoslavia, first cousin of Crown Prince Alexander
June
3rd, 40th birthday of Prince Félix of Luxembourg, son of the present Grand Duke
5th, 60 years ago the wedding of Baron Niclas Silfverschiöld and Princess Désirée of Sweden
5th, Silver wedding anniversary of Philipp von Lattorff and Princess Tatjana of Liechtenstein
6th, 100 years ago the birth of Mr John Ambler, brother-in-law of King Carl Gustaf of Sweden
8th, 40th birthday of Andrea Casiraghi, son of Princess Caroline of Monaco
6th, 90th birthday of King Albert II of Belgium
10th, 100 years ago the wedding of Prince Viggo of Denmark and Eleanor Margaret Green
10th, 50 years ago the passing of Prince Henry, Duke of Gloucester
15th, Golden wedding anniversary of Tord Magnuson and Princess Christina of Sweden
19th 10th anniversary on the throne of King Felipe of Spain
23rd, 50th birthday of Princess Carolina of Bourbon-Parma, sister of the present head
27th, 80th birthday of Jacques Nompar, Duke de La Force (France)
27th, 50th birthday of Christopher O´Neill, husband of Princess Madeleine of Sweden
27th, 50th birthday of Princess Desirée of Schaumburg-Lippe, granddaughter of Danish-born princess Feodora
28th, 30th birthday of Crown Prince Hussein of Jordan
30th, 60th birthday of Alexandra, Countess of Frederiksborg, former wife of Prince Joachim of Denmark
30th, 60 years ago the wedding of John Ambler and Princess Margaretha of Sweden
July
2nd, 65th wedding anniversary of King Albert and Queen Paola of Belgium
4th, 90th birthday of James Hamilton, 5th Duke of Abercorn
7th, 80th birthday of Nicholas, Prince of Montenegro
8th, Silver wedding anniversary of Prince Carl Christian (nephew of the Swedish King) and Princess Nicole of Hohenzollern
9th, 50th birthday of Prince Foulques of Orléans, Duke of Aumale
9th, Silver wedding celebrations of Princess Alexia of Greece and Carlos Morales
11th, 60th birthday of Kyril, Prince of Preslav (Bulgaria)
12th, 65th birthday of King Tupou VI of Tonga
13th, 60th birthday of Princess Maria of Romania
13th, 20th birthday of Prince Jean of Nassau, son of Prince Guillaume of Luxembourg
14th, 60 years ago the passing of Prince Axel of Denmark
14th, 30th wedding anniversary of Daniel Chatto and Lady Sarah Armstrong-Jones
15th, 100th birthday of Countess Marianne Bernadotte (Sweden)
17th, 20 years ago the passing of Susan, Crown Princess of Albania
23rd, 25 years anniversary on the throne of King Mohammed VI of Morocco
24th, 90th birthday of Princess Dorothea of Hessen, Princess of Windish-Grätz, first cousin of King Charles III of the United Kingdom
27th, 30th birthday of Mafalda-Cecilia von Saxe-Coburg-Gotha, oldest grandchild of Simeon, last King of Bulgaria
August
2nd (civ), October 29th (rel), 20th wedding anniversary of Countess Bettina Bernadotte and Philipp Haug
3rd, 70th birthday of Prince Albrecht of Hohenzollern, brother of the present head
5th, 85th birthday of Princess Irene of the Netherlands
8th, 200 years ago the birth of Princess Marie of Hesse and by Rhine, later first wife of Alexander II, Emperor of Russia
13th, 100 years ago the birth of Prince Alexander of Yugoslavia
13th, 30th birthday of Duke Wilhelm of Württemberg
17th, 100 years ago the birth of Prince Alfred of Prussia, grandson of Prince Heinrich and Princess Irene of Prussia
19th, 100 years ago the birth of Abdul Reza Pahlavi, half-brother of the last Shah of Iran
19th, 85th birthday of Prince Wilhelm of Schaumburg-Lippe, son of a Danish-born princess
21st, 100 years ago the birth of Gerald David Lascelles, first cousin of Queen Elizabeth II
21st, 80th birthday of Count Michael Bernadotte, first cousin to the Swedish King
23rd, 70th birthday of Haakon Lorentzen, grandson of late King Olav of Norway
26th, 80th birthday of Richard, Duke of Gloucester
26th, 70th birthday of Archduke Carl Christian of Austria
28th, 90th birthday of Prince Heinrich XI Licco of Reuss, descendant from the royal houses of Mecklenburg-Schwerin, Prussia, Russia etc.
September
2nd, 100th birthday of Princes Maria Christina of Liechtenstein, widow of Prince Georg
4th, 100 years ago the wedding of Claus Felix von Amsberg and Baroness Gosta von dem Bussche-Haddenhausen, paternal grandparents of King Willem-Alexander of the Netherlands
6th, 100 years ago the passing of Archduchess Marie Valerie of Austria, daughter of Emperor Franz Joseph I and Empress Elisabeth of Austria
7th, 20th wedding anniversary of Prince Ali bin Al Hussein and Princess Rym al-Ali of Jordan
8th, 110th anniversary of the birth of Pss D. Maria Francisca d'Orléans-Bragança, mother of the present Duke of Bragança
8th, 30th wedding anniversary of Prince Guillaume and Princess Sibilla of Luxembourg
9th (and 10th), Diamond wedding anniversary of Friedrich Karl Count von Schönborn-Buchheim and Princess Isabelle of Orléans
10th, 60th birthday of Princess Gisela of Bayern, Princess of Sachsen
13th, 70th birthday of Archduchess Monika of Austria, sister of the present head
13th, 70th birthday of Archduchess Michaela of Austria, sister of the present head
13th, 10th wedding anniversary of Hugo Wilson and Princess Maria Theresia of Thurn und Taxis (sister of the present head)
15th, 40th birthday of Prince Harry, Duke of Sussex
17th, 100 years ago the wedding of Prince Wolfgang of Hessen and Princess Marie Alexandra of Baden
17th, 90th birthday of Princess Helene of Orléans, Countess von Limburg-Stirum
17th, 20th birthday of Prince Odysseas Kimon of Greece
18th, 60 years ago the wedding of King Constantin of Greece and Princess Anne-Marie of Denmark
22nd, 60th birthday of Astrid of Bourbon-Parma, granddaughter of Danish-born princess Margrethe, Princess René of Bourbon-Parma
22nd, Ruby wedding anniversary of Archduke Lorenz of Austria-Este and Princess Astrid of Belgium
24th, 100 years ago the birth of Lady Mary Cambridge, later Lady Mary Whitley, relative of the British royal family
24th, 90th birthday of Princess Maria Pia of Bourbon-Parma, daughter of the last King of Italy
26th, 30 years ago the passing of Louis Ferdinand, Prince of Prussia (former head)
29th, Ruby wedding anniversary of Prince Christian-Sigismund and Princess Nina of Prussia
30th, Diamond wedding anniversary of Prince Masahito and Princess Hanako of Japan
October
8th, 100 years ago the birth of Alice Ruth Nielsen, later Countess of Rosenborg and daughter-in-law of Prince Axel and Princess Margaretha of Denmark
13th (civ), 15th (rel), 30th wedding anniversary of Stephan & Maria, Prince and Princess of Lippe
14th, 50th birthday of Princess Flora-Franziska of Hessen, wife of the present head of the House of Hessen
14th, 20 years anniversary on the throne of King Norodom Sihamoni of Cambodia
15th, 70th birthday of Princess Friederike of Hannover, Mrs Jerry William Cyr
17th, 80th birthday of Prince Franz Friedrich of Prussia, grandson of Prince Joachim of Prussia
18th, 70th birthday of Archduke Karl Philipp of Austria, first cousin to the present head
20th, 90th birthday of Michiko, Empress Emerita of Japan
23rd, 40th birthday of Princess Olga of Leiningen, daughter of the present head
24th, 50th birthday of Alexander, Earl av Ulster, son of the Duke of Gloucester
31st, 90th birthday of Princess Margaretha, Mrs Ambler (Sweden)
31st, 60th birthday of Countess Judith af Rosenborg
November
1st, 60th birthday of Duke Philipp of Württemberg
4th, 10 years ago the passing of Princess Kristine Bernadotte, wife of Prince Carl Bernadotte (Sweden)
10th, 70th birthday of Princess Sibyl of Bourbon-Parma
10th, 60 years ago the passing of Prince Pierre, Duke of Valentinois, paternal grandfather of the present Prince of Monaco
12th, 90th birthday of Marie Therese, Duchess of Monpensier (France)
17th, 50th birthday of Durek Verrett, future husband of Princes Märtha Louise of Norway
18th, 60th birthday of The Hon. Timothy Knatchbull, second cousin of King Charles III
23rd, 75th birthday of Gunilla Bismarck, paternal aunt to the present Fürst Bismarck
24th, 75th birthday of Princess Isabelle of Liechtenstein, sister-in-law of the present Fürst
25th, 25th birthday of Infante D.Diniz of Braganca, Duke of Porto
26th, 95th birthday of Ralf Sommerlath, brother of Queen Silvia of Sweden
26th, 80th birthday of Joachim, 8th Prince Murat, descendant of Napoleon´s sister Caroline
27th, 20th wedding anniversary of Eckbert von Bohlen und Halbach and Princess Désirée of Hohenzollern (niece of the Swedish king)
27th, 75th birthday of Count Archibald Douglas, husband of Archduchess Walburga von Habsburg
December
1st, 20 years ago the passing of Prince (consort) Bernhard of the Netherlands
3rd, 80th birthday of Salvador Moncada, husband of Princess Marie-Esmeralda of Belgium
4th, Silver wedding celebration of King Philippe and Queen Mathilde of Belgium
5th, 10 years ago the passing of Queen Fabiola of Belgium
6th, 40th birthday of Princess Sofia of Sweden, wife of Prince Carl Philip
10th, 10th birthday of Princess Gabriella and Jacques, Hereditary Prince of Monaco
11th, 70th birthday of Archduchess Maria Beatrix of Austria, Countess von Arco-Zinneberg
16th, 60th birthday of Archduke Georg of Austria
18th, 50th birthday of Tom Parker Bowles, son of Queen Camilla of the United Kingdom
20th, Golden wedding anniversary of Princess Edda of Anhalt and Albert Darboven
21st, 20 years ago the passing of Count Lennart Bernadotte, born Prince of Sweden
25th, 90th birthday of Prince Wolfgang of Liechtenstein, first cousin of late Fürst Franz Joseph II of Liechtenstein
26th, 35th birthday of Pss D. Maria Cristina d'Orléans-Bragança, daughter of Pr. D. João-Henrique
27th, 80th birthday of Prince Adalbert of Bavaria
28th, 75th birthday of Princess Yasmin Aga Khan, half-sister of Aga Khan IV
29th, 30th birthday of Princess Kako of Akishino, niece of the present Emperor of Japan
Sources of the dates:
Wikipedia
Gotha online
Genealogisches Handbuch Des Adels Fürstliche Hauser