The Star Trek franchise has made several references to the Doctor Who universe, and the two also share some behind-the-scenes commonalities.
References to Doctor Who in Star Trek narratives
- A computer console seen in the Star Trek: The Next Generation episode "The Neutral Zone" shows the names of the first six actors to play the Doctor. Peter Davison's name was misspelled as "Peter Davidson". Note: the remastered version of the episode, released to Blu-ray, removes this reference.
- The Argolis Cluster, first mentioned in the Next Generation episode "I Borg", was named after the planet Argolis. (TV: The Leisure Hive)
- "Future Tense", an episode of Star Trek: Enterprise, features a TARDIS-like 31st century spacecraft that can travel through time, is bigger on the inside than on the outside, and has an interior design featuring TARDIS-like roundels. The show's production team has acknowledged this as an homage. That episode's writer, Mike Sussman, noted that his "idea of the ship morphing into a police call box was immediately nixed by the producers!" 
Paramount Pictures, owner of the Star Trek franchise, does not consider anything other than the live action Star Trek television series and films canon. Nevertheless, there are licensed comic and prose stories, and these have very occasionally referenced the DWU.
- The Star Trek novel Ishmael makes an indirect reference to the Time Lords, a direct reference to Metebelis crystals and features cameos by the Second Doctor and the Fourth Doctor.
- Several Star Trek stories have mentioned "sonic screwdrivers" as Starfleet engineering tools. For instance, the Star Trek: Vanguard novel Harbinger, the Star Trek: Corps of Engineers eBook Wildfire and Star Trek: Titan novel Sword of Damocles.
- A direct reference to the Doctor Who franchise is made in the novel My Enemy, My Ally, which describes USS Enterprise crewmembers watching a Fourth Doctor episode.
- Christopher L. Bennett's novel Watching the Clock features a number of minor, but intentional, references to the DWU. .
- Time is described as "a big ball of wibbly-wobbly, time-wimey . . . stuff", as in TV: Blink.
- The character of Rani Mohindra is a conflation of the names Rani Chandra and Anjli Mohindra.
- A ship named the Verity appears, which Bennet claims to have named after producer Verity Lambert.
- The Shirna, archenemies of the already established Vogon, were named after Shirna, the partner of Vorg, who both appeared in TV: Carnival of Monsters.
- A "large, blue, boxlike artefact" is seen in a Federation storehouse of alien time travel devices.
- A planet is described as having "silver trees and an orange sky", with inhabitants who have been monitoring history for thousands of years — thus making it an apparent analogue of Gallifrey.
- The Tigellian chronic hysteresis is a reference to Tigella.
- Other extremely incidental references are also in the book, but they are obscured by bad spelling on the author's part (such as the fact that a character is supposedly named after Peter Purves, but spelled Purvis) or deliberate obfuscation (such as a unit of measurement named the "maloc", which is supposedly a tip of the hat to the "malcolm" from TV: Planet of the Dead)
Due to the two franchises being produced in different countries, shared cast members are rare. Most of the connections between the two franchises have occurred as a result of the three productions with extensive North American filming: the 1996 movie, TV: The Impossible Astronaut, and Torchwood: Miracle Day. Star Trek actors who crossed over because of these productions include Daphne Ashbrook, John de Lancie, Nana Visitor, Mark Sheppard and William Morgan Sheppard.
Conversely, several British actors appeared in the Star Trek franchise after their Doctor Who appearances. Perhaps the most high profile is Simon Pegg, who after appearing in TV: The Long Game as the Editor and narrating a series of Doctor Who Confidential, took over the role of Scotty from the 2009 film Star Trek onwards.
Finally, those such as Alexander Siddig and David Warner have crossed over into the DWU by virtue of voice acting work, typically for Big Finish Productions. In 2012, Chase Masterson debuted the character of Vienna Salvatori in AUDIO: The Shadow Heart, with a spin-off audio series which followed in 2013, making Masterson the first Star Trek actor to take an ongoing lead role in a Doctor Who spin-off. Masterson has also played other characters for Big Finish.
Rarely, people like Anthony Head have gone in the opposite direction with voice work, by reading audiobooks for the Star Trek franchise.
According to The Nth Doctor, in 1994, Leonard Nimoy, who played the original Mr. Spock and directed two Star Trek feature films, was reportedly under consideration to direct one of the many aborted Doctor Who feature film projects under consideration during the 1989-96 interregnum.
TV movie composer John Debney also composed scores for the Star Trek: The Next Generation episode "The Pegasus" and the Star Trek: Deep Space Nine episodes "The Nagus" and "Progress". Tony Dow, who worked as visual effects producer for the TV movie, later directed the Deep Space Nine episode "Field of Fire".
Torchwood: Miracle Day writers Jane Espenson and John Shiban have also written episodes for Deep Space Nine and Star Trek: Enterprise respectively. Other writers, such as Una McCormack, John Peel, Diane Duane and Keith R.A. DeCandido, have written for both franchises in other media.
Crossovers, planned and actual
In April 2009, Russell T Davies revealed in an interview that he had considered writing a Doctor Who episode that crossed over with Star Trek: Enterprise.
- "I would have loved to have done a Star Trek crossover," said Davies. "The very first year, we talked about it. Then Star Trek finally went off air. Landing the TARDIS on board the Enterprise would have been magnificent. Can you imagine what their script department would have wanted, and what I would have wanted? It would have been the biggest battle."
In 2012 IDW Publishing published an official 8-issue crossover series titled Star Trek: The Next Generation/Doctor Who: Assimilation² that featured the Eleventh Doctor and the Cybermen encountering the characters from Star Trek: The Next Generation, with one issue also featuring a flashback of the Fourth Doctor encountering characters from Star Trek: The Original Series. The first issue was released on 30 May 2012.
- The fan novella The Doctor and the Enterprise by Jean Airey, initially was published privately as a stand-alone fanzine and then in a professional edition in 1989 by Pioneer Books. Many other amateur fan fiction crossovers between the two universes have been written over the years, though Airey's book remains the only one to be published professionally, if unofficially. There would be no official crossover between the two franchises published until Assimilation² in 2012.
- Cast members of both Doctor Who and Star Trek have participated in special editions of the television game show, The Weakest Link, hosted by Anne Robinson.
- Albert Einstein has appeared in both franchises. In Doctor Who, he appears in Sylvester McCoy's debut story, Time and the Rani, and the 2011 mini-episode Death Is the Only Answer. In the Star Trek: The Next Generation episodes "The Nth Degree" and "Descent", he appears as a holographic projection. In the latter, he was played by Jim Norton, who later played Thomas Kennet in NOTDWU: Scream of the Shalka.
- As long running science fiction franchises, there have been occasional story elements with marked similarities.
- The cybernetic Borg assimilate species in similar fashion to the Cybermen and also use a similar catchphrase ("You will be assimilated"). Likewise, the warrior race of Klingons share similarities with the Sontarans and Draconians.
- The Trill also possess the ability to pass on a symbiont after a host body dies, allowing them to effectively live on after death, not entirely dissimilar from regeneration. When joined with a symbiont, the personality of the new host will change as it becomes an amalgamation of their own, plus those of their predecessors, as well as retaining all of their memories. Through specific rituals, it is also possible for the current hosts to interact with their predecessors, as seen in the Deep Space Nine episodes "Facets" and "Field of Fire", which were DS9 equivalents of multi-Doctor episodes. The ability of Trill to take on the memories and experiences of others was also utilised when Terry Farrell and her character of Jadzia Dax was replaced by Nicole de Boer's Ezri Dax, in much the same way Doctor actors are replaced when they choose to leave the series.
- In a Top Gear "Master of the Universe" segment, a Klingon raced around the Top Gear track against a Dalek, a Cyberman and Colin Baker as the Sixth Doctor (as well as Darth Vader from Star Wars and Ming the Merciless from Flash Gordon).
- Star Trek, for mentions and allusions to the Star Trek franchise in Doctor Who stories
- Memory Alpha, a Star Trek wiki focusing on the television and films
- Memory Alpha's page on Doctor Who
- Memory Beta, a Star Trek wiki focusing on the expanded media, such as books and comics.
- Memory Beta's page on Doctor Who
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