The September 11 attacks were a series of terrorist attacks by the Islamic terrorist group al-Qaeda against the United States on the morning of Tuesday, September 11, 2001, in which nearly 3,000 people were killed. Jokes based on the events have been made in print and other media since soon after the attacks took place.

A number of scholars have studied the ways in which humor has been used to deal with the trauma of the event, including researcher Bill Ellis who found that jokes about the attacks originating in the U.S. the day afterwards, and Giselinde Kuipers found jokes on Dutch websites a day later. Kuipers had collected around 850 online jokes about 9/11, Osama Bin Laden, and the Afghanistan war by 2005. A notable early public attempt at 9/11 humor was by Gilbert Gottfried just a few weeks after the attacks. During a comedy roast for Hugh Hefner at the Friars Club the crowd did not respond well to Gottfried's 9/11 gag. One audience member at the club yelled out "Too soon!", which has since become a common response to jokes told in the immediate wake of tragedies. Gottfried then improvised and performed "The Aristocrats" routine, which released a great deal of tension and got rousing applause from the crowd.

In contrast to these early jokes about 9/11, late-night comedy shows and humorous publications did not appear for several weeks following the attacks. The Onion, a satirical newspaper, cancelled the issue that had been scheduled to be released on September 11, 2001, and then returned to print with a special edition on September 26, 2001, which was devoted to the attacks. When the issue was released, the newspaper staff felt trepidation over making humor of such a tragic event. "Everyone thought this would be our last issue in print," according to one staff writer. Despite this expectation, The Onion staff was quickly inundated with comments from readers, the vast majority of which were positive. However, they self-censored the article titled "America Stronger Than Ever, Say Quadragon Officials."

One of the first 9/11 jokes was one told by Joan Rivers, a major American comedian, in London in 2002. The joke concerned the widows of fire fighters killed in the attacks, who Rivers said would be disappointed if their husbands had been found alive as they would be forced to return money they had received in compensation for their late spouses. The joke received condemnation from Harold Schaitberger, General President of the International Association of Fire Fighters.