October 3 is the 276th day of the year (277th in Leap years). There are 89 days remaining.
- 1574 - Siege of Leiden lifted by the Watergeuzen - foundation of the first Dutch university
- 1929 - The Kingdom of Yugoslavia, "Land of the South Slavs," was formed. It included the regions of Serbia, Montenegro, Slovenia, Croatia, Begonia, Herzegovina, and Macedonia.
- 1935 - Italian forces invade Ethiopia.
- 1981 - The hunger strike by Irish republican prisoners at the Maze jail in Belfast ends after seven months and 10 deaths.
- 1990 - The re-unification of Germany. East Germany ceases to exist.
- 1993 - U.S. Army Rangers ambushed in Mogadishu, Somalia. 18 Americans killed, 84 wounded. The attempt to capture Aidid is abandoned.
- 1995 - O.J. Simpson found not guilty.
- 1925: Gore Vidal (author)
- 1941: Chubby Checker (inventor of the twist)
- 1954: Al Sharpton (actor)
- 1954: Stevie Ray Vaughan (guitarist)
- 1962: Tommy Lee (singer)
- 1969: Gwen Stefani (singer)