| 45903 | April 20 | Death | 2014 – Neville Wran, Australian lawyer and politician, 35th Premier of New South Wales (b. 1926) |
| 45904 | April 20 | Death | 2015 – Richard Anthony, Egyptian-French singer-songwriter (b. 1938) |
| 45905 | April 20 | Death | 2015 – Doug Buffone, American football player and sportscaster (b. 1944) |
| 45906 | April 20 | Death | 2015 – Aharon Lichtenstein, French-Israeli rabbi and author (b. 1933) |
| 45907 | April 20 | Death | 2015 – Frederic Morton, Austrian-American banker, journalist, and author (b. 1924) |
| 45908 | April 20 | Death | 2015 – Bob St. Clair, American football player and politician (b. 1931) |
| 45909 | April 20 | Holiday and observance | Christian feast day:Agnes of MontepulcianoBlessed Oda of BrabantJohannes Bugenhagen (Lutheran)TheotimosApril 20 (Eastern Orthodox liturgics) |
| 45910 | April 20 | Holiday and observance | Ridván begins at sunset (Bahá'í Faith) |
| 45911 | April 20 | Holiday and observance | UN Chinese Language Day (United Nations) |
| 45912 | April 20 | Holiday and observance | 4/20 (International cannabis culture holiday) |
| 45913 | April 21 | Event | 753 BC – Romulus founds Rome (traditional date). |
| 45914 | April 21 | Event | 43 BC – Battle of Mutina: Mark Antony is again defeated in battle by Aulus Hirtius, who is killed. Antony fails to capture Mutina and Decimus Brutus is murdered shortly after. |
| 45915 | April 21 | Event | 900 – The Laguna Copperplate Inscription (the earliest known written document found in what is now the Philippines): the Commander-in-Chief of the Kingdom of Tondo, as represented by the Honourable Jayadewa, Lord Minister of Pailah, pardons from all debt |
| 45916 | April 21 | Event | 1092 – The Diocese of Pisa is elevated to the rank of metropolitan archdiocese by Pope Urban II |
| 45917 | April 21 | Event | 1506 – The three-day Lisbon Massacre comes to an end with the slaughter of over 1,900 suspected Jews by Portuguese Catholics. |
| 45918 | April 21 | Event | 1509 – Henry VIII ascends the throne of England on the death of his father, Henry VII. |
| 45919 | April 21 | Event | 1526 – The last ruler of the Lodi dynasty, Ibrahim Lodi is defeated and killed by Babur in the First Battle of Panipat. |
| 45920 | April 21 | Event | 1615 – The Wignacourt Aqueduct is inaugurated in Malta. |
| 45921 | April 21 | Event | 1782 – The city of Rattanakosin, now known internationally as Bangkok, is founded on the eastern bank of the Chao Phraya River by King Buddha Yodfa Chulaloke. |
| 45922 | April 21 | Event | 1792 – Tiradentes, a revolutionary leading a movement for Brazil's independence, is hanged, drawn and quartered. |
| 45923 | April 21 | Event | 1806 – Action of 21 April 1806: A French frigate escapes British forces off the coast of South Africa. |
| 45924 | April 21 | Event | 1809 – Two Austrian army corps are driven from Landshut by a First French Empire army led by Napoleon as two French corps to the north hold off the main Austrian army on the first day of the Battle of Eckmühl. |
| 45925 | April 21 | Event | 1821 – Benderli Ali Pasha arrives in Constantinople as the new Grand Vizier of the Ottoman Empire he remains in power for only nine days before being sent into exile. |
| 45926 | April 21 | Event | 1836 – Texas Revolution: The Battle of San Jacinto: Republic of Texas forces under Sam Houston defeat troops under Mexican General Antonio López de Santa Anna. |
| 45927 | April 21 | Event | 1856 – Australian labour movement: Stonemasons and building workers on building sites around Melbourne march from the University of Melbourne to Parliament House to achieve an eight-hour day. |
| 45928 | April 21 | Event | 1863 – Bahá'u'lláh, the founder of the Bahá'í Faith, declares his mission as "He whom God shall make manifest". |
| 45929 | April 21 | Event | 1894 – Norway formally adopts the Krag–Jørgensen bolt-action rifle as the main arm of its armed forces, a weapon that would remain in service for almost 50 years. |
| 45930 | April 21 | Event | 1898 – Spanish–American War: The United States Navy begins a blockade of Cuban ports. When the U.S. Congress issued a declaration of war on April 25, it declared that a state of war had existed from this date. |
| 45901 | April 20 | Death | 2014 – Benedikt Sarnov, Russian author and critic (b. 1927) |
| 45902 | April 20 | Death | 2014 – Peter Scoones, English photographer and cinematographer (b. 1937) |