An egg of Columbus or Columbus's egg (Italian: uovo di Colombo [ˈwɔːvo di koˈlombo]) refers to a brilliant idea or discovery that seems simple or easy after the fact. The expression refers to an apocryphal story, dating from at least the 16th century, in which it is said that Christopher Columbus, having been told that finding a new trade route was inevitable and no great accomplishment, challenges his critics to make an egg stand on its tip. After his challengers give up, Columbus does it himself by tapping the egg on the table to flatten its tip.

The story is often alluded to when discussing creativity. The term has also been used as the trade name of a tangram puzzle and several mechanical puzzles. It also shows that anything can be done by anyone with the right set of skills; however, not everyone knows how to do it.