The 2005 ECW One Night Stand was the inaugural One Night Stand professional wrestling pay-per-view (PPV) event produced by World Wrestling Entertainment (WWE). It took place on June 12, 2005, at the Hammerstein Ballroom in the Manhattan borough of New York City, New York. Although wrestlers from WWE's Raw and SmackDown! brands appeared on the show, the event was primarily produced as a reunion show for wrestlers from the former Extreme Championship Wrestling (ECW) promotion, which had folded in 2001. After the promotion's closure, WWE acquired ECW's assets in 2003.

The main event was a tag team match between Dudley Boyz (Bubba Ray and D-Von) and the team of Tommy Dreamer and The Sandman. Two of the matches on the undercard were Chris Benoit versus Eddie Guerrero, and Mike Awesome versus Masato Tanaka.