A teaser trailer, or teaser is a short trailer used to advertise an upcoming movie, game or television series.

Teasers, unlike typical theatrical trailers, are usually very short in length (between 30–60 seconds) and usually contain little if any actual footage from the film. Sometimes it is merely a truncated version of a theatrical trailer. They are usually released long in advance of the film they advertise.

Teaser trailers are usually only made for big-budget and popularly themed movies. Their purpose is less to tell the audience about a movie's content than simply to let them know that the movie is coming up in the near future, and to add to the hype of the upcoming release. Teaser trailers are often made while the film is still in production or being edited and as a result they may feature scenes or alternate versions of scenes that are not in the finished film. Teaser trailers today are increasingly focused on internet downloading and the convention circuit.

An early example of the teaser trailer was the one for the Superman film by Richard Donner. The film was already nearly a year late; it was designed to re-invigorate interest in the release. The teaser for the Batman film starring Michael Keaton in 1989 was an emergency marketing move that successfully convinced angered comic book fans that the film would respect the source material.

Recent examples of major motion picture events that used teaser trailers to gain hype are the Lord of the Rings trilogy, the Disney/Pixar film Cars, the newer Star Wars films and the Spider-Man films. The Da Vinci Code teaser trailer was released before a single frame of the movie had been shot.

Some teasers have appeared over a year prior to the movie's release date. (For example, a teaser for The Incredibles was attached to the May 2003 film Finding Nemo, a full 18 months before The Incredibles was released.)

A teaser for Star Wars Episode I: The Phantom Menace was attached to the film The Siege, and it was reported that many people had paid for admission to the film just to watch the trailer, and had walked out after the trailer had screened blank">http://www.cnn.com/SHOWBIZ/Movies/9811/20/star.wars.01/.

Many DVD versions of movies will have both their teaser and theatrical trailers. One of the more notable exceptions to this rule is _Spider-Man, whose teaser trailer featured a mini-movie plot of bank robbers escaping in a helicopter, getting caught from behind and propelled backward into what at first appears to be a net, then is shown to be a gigantic spider web spun between the two towers at the World Trade Center. After the 9/11 attacks, the trailer and associated teaser poster (where the two towers appear in as a reflection in Spider-Man's eyepieces) were pulled from distribution in theaters and have never been released on DVD. Conducting a search on YouTube under "Spider-man Banned Trailer" will show the teaser trailer in its entirety.

Many teaser trailers are similar to TV spots, except that they appear in movie theatres.