| 121021 | October 22 | Death | 2015 – Willem Aantjes, Dutch civil servant and politician (b. 1923) |
| 121022 | October 22 | Death | 2015 – Çetin Altan, Turkish journalist and politician (b. 1927) |
| 121023 | October 22 | Death | 2015 – Murphy Anderson, American illustrator (b. 1926) |
| 121024 | October 22 | Death | 2015 – Arnold Klein, American dermatologist and author (b. 1945) |
| 121025 | October 22 | Death | 2015 – Mark Murphy, American singer-songwriter and actor (b. 1932) |
| 121026 | October 22 | Death | 2015 – Joshua Wheeler, American sergeant (b. 1975) |
| 121027 | October 22 | Holiday and observance | Christian feast day:Aaron the Illustrious (Syriac Orthodox Church)Abercius of HieropolisBerthariusDonatus of FiesolePope John Paul IIMary SalomeNunilo and AlodiaOctober 22 (Eastern Orthodox liturgics) |
| 121028 | October 22 | Holiday and observance | Earliest day on which New Zealand's Labour Day can fall, while October 28 is the latest celebrated on the fourth Monday in October (New Zealand) |
| 121029 | October 22 | Holiday and observance | Earliest day on which Make a Difference Day can fall, while October 28 is the latest celebrated on the fourth Saturday in October (United States) |
| 121030 | October 22 | Holiday and observance | Spiritual New Year, in Eckankar |
| 121031 | October 22 | Holiday and observance | Fechner Day, celebrated by Psychophysicists |
| 121032 | October 22 | Holiday and observance | International Stuttering Awareness Day (International) |
| 121033 | October 22 | Holiday and observance | Jidai Matsuri (Kyoto) |
| 121034 | October 22 | Holiday and observance | Wombat Day |
| 121035 | October 23 | Event | 42 BC – Liberators' civil war: Second Battle of Philippi – Mark Antony and Octavian decisively defeat Brutus's army. Brutus commits suicide. |
| 121036 | October 23 | Event | 425 – Valentinian III is elevated as Roman emperor at the age of six. |
| 121037 | October 23 | Event | 501 – The Synodus Palmaris, called by Gothic king Theoderic the Great, discharges Pope Symmachus of all charges, thus ending the schism of Antipope Laurentius. |
| 121038 | October 23 | Event | 1086 – At the Battle of Sagrajas, the army of Yusuf ibn Tashfin defeats the forces of Castilian King Alfonso VI. |
| 121039 | October 23 | Event | 1157 – The Battle of Grathe Heath ends the civil war in Denmark. King Sweyn III is killed and Valdemar I restores the country. |
| 121040 | October 23 | Event | 1295 – The first treaty forming the Auld Alliance between Scotland and France against England is signed in Paris. |
| 121041 | October 23 | Event | 1641 – Irish Catholic gentry from Ulster tried to seize control of Dublin Castle, the seat of English rule in Ireland, to force concessions to Catholics. |
| 121042 | October 23 | Event | 1642 – Battle of Edgehill: First major battle of the First English Civil War. |
| 121043 | October 23 | Event | 1694 – British/American colonial forces, led by Sir William Phips, fail to seize Quebec from the French. |
| 121044 | October 23 | Event | 1707 – The first Parliament of Great Britain meets. |
| 121045 | October 23 | Event | 1739 – War of Jenkins' Ear starts: British Prime Minister Robert Walpole, reluctantly declares war on Spain. |
| 121046 | October 23 | Event | 1812 – Claude François de Malet, a French general, begins a conspiracy to overthrow Napoleon Bonaparte, claiming that the Emperor died in Russia and that he is now the commandant of Paris. |
| 121047 | October 23 | Event | 1850 – The first National Women's Rights Convention begins in Worcester, Massachusetts, United States. |
| 121048 | October 23 | Event | 1861 – U.S. President Abraham Lincoln suspends the writ of habeas corpus in Washington, D.C., for all military-related cases. |
| 121049 | October 23 | Event | 1864 – American Civil War: Battle of Westport: Union forces under General Samuel R. Curtis defeat Confederate troops led by General Sterling Price at Westport, near Kansas City. |
| 121050 | October 23 | Event | 1867 – Seventy-two Senators are summoned by Royal Proclamation to serve as the first members of the Canadian Senate. |