Nightline (or ABC News Nightline) is ABC News' late-night television news program broadcast on ABC in the United States with a franchised formula to other networks and stations elsewhere in the world. Created by Roone Arledge, the program featured Ted Koppel as its main anchor from March 1980 until his retirement in November 2005. Its ongoing rotating anchors are Byron Pitts and Juju Chang. Nightline airs weeknights from 12:37 to 1:07 a.m., Eastern Time, after Jimmy Kimmel Live!, which had served as the program's lead-out from 2003 to 2012.

In 2002, Nightline was ranked 23rd on TV Guide's 50 Greatest TV Shows of All Time. The program has won four Peabody Awards, one in 2001, two in 2002 for the reports "Heart of Darkness" and "The Survivors," and one in 2022 for "The Appointment".

Through a video-sharing agreement with the BBC, Nightline repackages some of the BBC's output for an American audience. Segments from Nightline are shown in a condensed form on ABC's overnight news program World News Now. There was also a version of Nightline for sister cable channel Fusion.