Twilight

Twilight is the time of day shortly after sunset or before sunrise, where it isn't as bright as day, but it's also not as dark as night. You... probably weren't referring to this meaning when you came here. Then again...

On all The Tropes, "Twilight" could mean:

Anime and Manga

 * "Twilight" - the army led by Nene Amano in Digimon Xros Wars.

Comic Books

 * Twilight (Comic Book) - a comic book miniseries by Howard Chaykin.
 * "Twilight" - the name of the Big Bad in the Season 8 Buffy the Vampire Slayer comics.

Film

 * Twilight - A 1998 thriller/noir starring Paul Newman, Gene Hackman, Susan Sarandon and a briefly topless Reese Witherspoon
 * The Twilight Saga (film series) - A series of four films based on the novels by Stephanie Meyer

Literature

 * Twilight (novel) - a four-book saga about sparkly vampires and the girls who love them; also has film adaptations. Rather popular among the teen girl crowd.
 * Twilight - a novel by Dmitry Glukhovsky (also known as the author of Metro 2033).
 * Twilight - one of the novels in the Warrior Cats series
 * "Twilight" - a 1934 short story by John W. Campbell that warns against technological decadence.
 * "Twilight" - The original title of Dean Koontz's 1988 novel The Servants of Twilight.
 * Twilight - The name of a character in the Guardians of Ga'Hoole series.

Music

 * Twilight - a name of quite a few music artists, including one supergroup.
 * "Twilight" - a song by Electric Light Orchestra on their Concept Album Time.

Tabletop Games

 * Twilight 2000: A Tabletop RPG set After the End.

Western Animation

 * Twilight Sparkle - The protagonist of My Little Pony Friendship Is Magic, not to be confused about another Twilight (novel) that involves sparkling.