(written from a Production point of view)
Many projects have been partially developed for Star Trek beginning in the 1970s. There have also been deleted scenes for completed projects.
- Star Trek: Planet of the Titans (1976-1977)
- Star Trek: The First Adventure (1989)
- Star Trek: IMAX (1997)
- Star Trek: The Beginning (2005)
Untitled movie project Edit
Gene Roddenberry approached Paramount Pictures with the idea of a Star Trek movie as early as 1973. Roddenberry wanted Herb Solow (formerly the Desilu executive in charge of production on the first two seasons of Star Trek) to produce the film. He also wanted Solow to negiotiate with Paramount in his behalf. Roddenberry based the plot idea on the outline "A Question of Cannibalism" in his 1964 series proposal, Star Trek is... (the title was reworked as "The Cattlemen"). Solow thought the script had to be heavily rewritten, because "it did not foreshadow an enjoyable night at the movies". Despite this, Paramount was eager on the project, however Roddenberry refused to accept the screenwriting fee and equity proposed by the studio. After several unsuccessful negiotiations, Paramount backed away from the project and the movie was never made. Solow commented that the studio could've made the film without Roddenberry, but they did not want to alienate the fanbase. (Inside Star Trek: The Real Story, pp. 420-421, 430)
Star Trek: The Next Generation - The Movie Edit
A draft of this never-produced 'first' TNG film was developed by Rick Berman and Maurice Hurley in 1993. A draft of this untitled film was writted by Hurley in October 1993, but the project never moved forward. Berman published an image on Twitter of the drafted script in August 2014. 
An eleventh Star Trek movie was initially planned during production on the tenth film, Star Trek Nemesis. Nemesis co-writers John Logan and Brent Spiner intended to follow that film with a "crossover" sequel. After Nemesis failed financially, however, this plan was abandoned. 
Live-action television series Edit
- Assignment: Earth (1967-1968) 
- There were some plans for a fourth season of Star Trek: The Original Series, including a second episode featuring Kor, that would have aired 1969-1970.
- During the second season of The Original Series, Gene Roddenberry and Darlene Hartman (writer of unproduced episode "Shol") came up with an idea for a spin-off series entitled Hopeship, which would have been about the voyages of a Federation hospital vessel. The series would have included Doctor M'Benga (Booker Bradshaw) in the regular cast. Despite the series concept never being realized within the Star Trek universe, Hartman later wrote the idea in the form of a novel in 1994. (These Are the Voyages: TOS Season Two)
- According to Walter Koenig, NBC briefly considered making a spin-off series centered around the adventures of Harry Mudd, as the character proved to be popular, but these plans were quickly abandoned.  Mudd actor Roger C. Carmel learned of the idea from Gene Roddenberry, at a going-away party Desilu gave Herb Solow, after TOS was cancelled. Carmel subsequently recalled, "Gene said, 'It's a shame that series thing for you never worked out.' I said, 'What series thing?' He said, 'Oh, didn't you know!? Well, after the successful Harry Mudd episodes [in TOS], NBC wanted to know if I would develop a spin-off series for you starring the Harry Mudd character. A space pirate, intergalactic con-man kind of thing.' 'My God, Gene, I didn't know anything about that! What happened?' He said, 'Well, the artists didn't have enough time to develop it.' And of course, you couldn't blame Gene, he didn't want to let somebody take it off in a direction he didn't approve of. Since he didn't have time to handle it all, the Mudd series project died. But it was a real blow to me, because that was the first time I had heard of it. But what a great chance that would have been for me to star in my own spin-off series." (Starlog, issue #127, p. 33)
- Shortly after the cancellation of TOS, Paramount proposed a spin-off series centered on the character of Spock, featuring him living on Vulcan with other Vulcans. This idea was turned down by Gene Roddenberry, who Paramount had asked to produce the series. (The Making of Star Trek: The Motion Picture, p. 18)
- Star Trek: Phase II (1977)
- Before the creation of Star Trek: The Next Generation, Paramount showed Roddenberry a script for a possible new Star Trek television series involving the Enterprise being run by a group of cadets. Roddenberry was against this. ("Gene Roddenberry - The Creator of Star Trek: The Next Generation", The Official Star Trek: The Next Generation Magazine Vol. 1, p. 4)
- An idea for a Star Trek sitcom featuring Lwaxana Troi was suggested by Gene Roddenberry as a cable TV project for the Sci-Fi Channel in 1991. However, his death and the delay in setting up the channel shelved that. (citation needed • edit)
- There were some plans for a fifth season of Star Trek: Enterprise, which would have aired 2005-2006.
- Undeveloped Star Trek episodes
- Babylon 5 creator J. Michael Straczynski and Bryce Zabel (Dark Skies) proposed a reboot of the franchise with the crew of the original series in 2004 . Paramount ignored the proposal, though, as they were not "even willing to talk about Star Trek." 
- Jonathan Frakes developed an idea for a Star Trek series that was rejected by Paramount, who stated that they had previously rejected proposals by William Shatner and Bryan Singer out of concern of "franchise fatigue". Frakes agreed that this was a wise decision. "Not that [I] wouldn't love the Titan, or the Rikers in Space, or any of those shows on the air," he commented. 
- Bryan Singer, Christopher McQuarrie, Robert Meyer Burnett, and Geoffrey Thorne planned to pitch their own show entitled Star Trek: Federation, but they chose not to after development of the film Star Trek was announced. 
- Michael Dorn pitched The Worf Chronicles, a spin-off concentrating on the politics and feuds in the Klingon Empire. 
Animated Star TrekEdit
- Star Trek: Final Frontier (2006)
Before the making of Star Trek: The Animated Series was given the go-ahead, one concept for an animated series that was offered to Gene Roddenberry involved the Enterprise crew landing on strange planets and shooting everything on sight that was different or seemed ugly. (The Making of Star Trek: The Motion Picture, p. 18)
1990 animated Star TrekEdit
In 1990, Paramount Pictures attempted to sell an idea for an animated series that combined characters from Star Trek: The Next Generation and Star Trek: The Original Series. None of the networks or syndicators at the time were interested in the series and it was unsold. Rick Berman said such a project would have "diluted the franchise."
Cel art from this series has been seen in various Star Trek conventions over the years, and it has been stated to be well-drawn.
CGI cartoon based on the original seriesEdit
In the late 1990s, Paramount briefly considered creating a CGI original series cartoon, inspired by the success of Roughnecks: Starship Troopers Chronicles, and art (using motion-capture for the characters) of the unreleased game Star Trek: Secret of Vulcan Fury. 
Animated Ferengi seriesEdit
Around 2000 or 2001, Armin Shimerman and a friend of his devised an idea for an animated series about the teenage years in the lifetimes of the Ferengi Quark and Rom. "We got pretty far with that," stated Shimerman, "but in the end, when we got to the last pitch session with MTV, they said they didn't want a space cartoon show. But everyone was very happy with the ideas that we had come up with." (Star Trek Explorer, Vol. 4, No. 4, p. 11)
Star Trek: The Lions of the NightEdit
Around 2003, Star Trek: The Lions of the Night was a concept, by writer Jimmy Diggs, to produce a movie-era, CGI, animated Star Trek adventure. He described the plot the following way; "Captain Sulu takes command of the USS Enterprise-B and must stop a Kzinti invasion of Federation Space." Artist Court Jones created several sketches to depict a new concept of Kzinti that were looking more dangerous as well as a concept of how the Kzinti assault fleet would look.
The material of this animated series was recycled by the writer for an article in Star Trek: Communicator (Star Trek: Communicator issue 149) and later for undeveloped Star Trek: Enterprise season five episode "Kilkenny Cats".
Alternate reality seriesEdit
After the release of the film Star Trek, Roberto Orci and Alex Kurtzman pitched an animated series to CBS, similar to their series Transformers: Prime for The Hub.  However, Orci said the success of the first film did not indicate whether a new show would be viable, explaining, "One movie doesn't make a trend. Two movies starts to indicate that there is a trend and its viable. It will become more real as the year goes on." 
In 2013, a CBS Studios representative reiterated interest in reviving Star Trek for television, in response to a comment from J.J. Abrams that he had heard the studio was not interested.  A year later, Brannon Braga commented, "I surmise they probably won't do one until the movies have run their course is what the word on the street is," while Rod Roddenberry said he believed there would not be another series until after the conclusion of the films.