# 31 October 1984 – Indian Prime Minister Indira Gandhi is assassinated by two Sikh security guards. Riots break out in New Delhi and other cities and around 3,000 Sikhs are killed.

# 30 October 1961 – The Soviet Union detonates the Tsar Bomba, the most powerful explosive device ever detonated.

# 29 October 1675 – Leibniz makes the first use of the long s (∫) as a symbol of the integral in calculus.

‌# 28 October 1886 – President Cleveland dedicates the Statue of Liberty.

‌‌# 2‌7 October 2017 – Catalonia declares independence from Spain.

‌‌# 2‌6 October 1979 – Park Chung-hee, President of South Korea, is assassinated by Korean CIA head Kim Jae-gyu.

‌‌# 2‌5 October 1977 - ‌OpenVMS is a closed-source, proprietary computer operating system for use in general-purpose computing. It is the successor to the VMS Operating System (VAX-11/VMS, VAX/VMS), that was produced by Digital Equipment Corporation, and first released in 1977 for its series of VAX-11 minicomputers.

‌# 24 October 1945 – Founding of the United Nations.

# 23 October 1917 – Lenin calls for the October Revolution.

# 22 October 1964 – Jean-Paul Sartre is awarded the Nobel Prize in Literature, but turns down the honor.

# 21 October 1994 – In Seoul, 32 people are killed when the Seongsu Bridge collapses.

# 20 October 1854 – Arthur Rimbaud, French soldier and poet (d. 1891)

# 19 October 1956 – The Soviet Union and Japan sign a Joint Declaration, officially ending the state of war between the two countries that had existed since August 1945.

# 18 October 1963 – Félicette, a black and white female Parisian stray cat becomes the first cat launched into space.

# 17 October 1558 – Poczta Polska, the Polish postal service, is founded.

# 16 October 1923 – The Walt Disney Company is founded.

# 15 October 2003 – China launches Shenzhou(simplified Chinese: 神舟五号; traditional Chinese: 神舟五號) 5, its first manned space mission.

# 14 October 1944 – World War II: Linked to a plot to assassinate Adolf Hitler, Field Marshal Erwin Rommel is forced to commit suicide.

# 13 October 1983 – Ameritech Mobile Communications launches the first US cellular network in Chicago.

# 12 October 1971 – The 2,500 year celebration of the Persian Empire begins.

# 11 October 1986 – Ronald Reagan and Mikhail Gorbachev meet in Iceland to continue discussions about scaling back IRBM arsenals in Europe.

# 10 October 1928 – Chiang Kai-shek becomes Chairman of the Republic of China.

# 09 October 1446 – The hangul alphabet is published in Korea.

# 08 October 1895 – Korean Empress Myeongseong is assassinated by Japanese infiltrators.

# 07 October 1919 – KLM, the flag carrier of the Netherlands, is founded. It is the oldest airline still operating under its original name.

# 06 October 2010 – Instagram, a mainstream photo-sharing application, is founded.

# 05 October 1550 – Foundation of Concepción, Chile.

# 04 October 1883 – First run of the Orient Express.

# 03 October 2457 BC – Gaecheonjeol, Hwanung (환웅) purportedly descended from heaven. South Korea's National Foundation Day.

# 02 October 2007 – President Roh Moo-hyun of South Korea goes to North Korea for an Inter-Korean summit with North Korean leader Kim Jong-il.

# 01 October 1946 – The Daegu October Incident occurs in Allied-occupied Korea.