星际大战日（英语：Star Wars Day），一个非官方的纪念日，在每年5月4日庆祝。最早在2011年由星际大战的电影影迷自行发起。

这个纪念日来自于星际大战电影中的一句经典台词「愿原力与你同在」（May the Force be with you），影迷取其谐音，变成「于五月四日与你同在」（May the fourth be with you），将这个日子订为纪念日。

Star Wars Day, May 4, celebrates Star Wars created by George Lucas. It is observed by fans of the films. Observance of the holiday spread quickly through Internet, social media, and grassroots celebrations.

The date was chosen for the easy pun on the catchphrase "May the Force be with you"— "May the Fourth be with you". Even though the holiday was not actually created or declared by Lucasfilm, many Star Wars fans across the world choose to celebrate the holiday.