War of the Worlds '15 was a two-day professional wrestling supershow co-produced by the American Ring of Honor (ROH) and Japanese New Japan Pro-Wrestling (NJPW) promotions. The events took place on May 12 and 13, 2015, at the 2300 Arena in Philadelphia, Pennsylvania, U.S. Both nights were released by ROH on video on demand (VOD) the following week. War of the Worlds '15 was the second annual War of the Worlds event co-produced by ROH and NJPW, following War of the Worlds, which took place on May 17, 2014, at the Hammerstein Ballroom in New York City.