History Main / WrittenByCastMember

** Andrew Robinson, who played Elim Garak in ''Series/StarTrekDeepSpaceNine'', wrote a spin-off novel, ''A Stitch in Time'', centering on the character.

** Armin Shimmerman, who played Quark in ''Deep Space Nine'', co-wrote ''The 34th Rule'' with David R. George III. In addition to starring Quark, it cameos a number of other Ferengi characters that Shimmerman had earlier played in different episodes of ''Star Trek: The Next Generation'', with Quark insisting they only look alike to ''hew-mons''.

[[folder:Literature]]
* Paul Darrow, who played Avon in ''Series/BlakesSeven'', wrote an officially-licensed spin-off novel, ''Avon: A Terrible Aspect'', which gives his own preferred version of his character's [[OriginsEpisode pre-show backstory]].
* ''Franchise/DoctorWhoExpandedUniverse'':
** Creator/IanMarter, who played Dr. Harry Sullivan, subsequently wrote nine of the Literature/DoctorWhoNovelisations, two of which ("[[Recap/DoctorWhoS12E2TheArkInSpace The Ark in Space]]" and "[[Recap/DoctorWhoS12E3TheSontaranExperiment The Sontaran Experiment]]") he had appeared in as Harry. Marter also wrote an entirely original novel featuring Harry as the protagonist, ''Harry Sullivan's War''. Marter and Creator/TomBaker co-wrote a speculative script for a ''Doctor Who'' movie during their time together on the show, called ''Literature/DoctorWhoMeetsScratchman'', which eventually ended up as a novel called simply ''Scratchman'' -- as Marter had died in the meantime the novelisation was a collaboration between Baker and Whoniverse writer James Goss.
** Creator/SophieAldred, who played Ace, wrote the Literature/NewSeriesAdventures novel ''At Childhood's End'', in which Ace is reunited with the Thirteenth Doctor.
* Has happened a few times in the ''Franchise/StarTrek'' franchise:
** Andrew Robinson, who played Elim Garak in ''Series/StarTrekDeepSpaceNine'', wrote a spin-off novel, ''A Stitch in Time'', centering on the character.
** J G Hertzler, who played several roles in the franchise, most notably the Klingon military officer and politician Martok and the outlaw Founder Laas in ''Deep Space 9'', co-wrote two novels centering on Martok.
** Creator/WilliamShatner, who played Captain Kirk, co-wrote a series of novels known as the "Shatnerverse", which take place in an AlternateTimeline in which Kirk is resurrected after his main-canon death in ''Film/StarTrekGenerations''.
** Armin Shimmerman, who played Quark in ''Deep Space Nine'', co-wrote ''The 34th Rule'' with David R. George III. In addition to starring Quark, it cameos a number of other Ferengi characters that Shimmerman had earlier played in different episodes of ''Star Trek: The Next Generation'', with Quark insisting they only look alike to ''hew-mons''.
** Creator/JohnDeLancie, who played Q, co-wrote ''Literature/{{IQ}}'' with Creator/PeterDavid.
[[/folder]]

* ''AdventureTime'':

* Three of ''Series/{{CSINY}}'' cast members tried their hands at writing episodes. Creator/GarySinise worked on the story line for "Live or Let Die" about a stolen donor liver, and wrote the screenplay for "Turbulence" in which a man posing as an Air Marshall is killed during a flight that Mac is on. Creator/MelinaKanakaredes wrote "Grounds for Deception" where Stella goes to Greece chasing a suspect - an ep which unfortunately drew mixed reviews from fans. Finally, Creator/CarmineGiavinazzo wrote "Sanguine Love," about the murder of a member of a vampire-like cult. This one was much better received by viewers.

* Creator/JerryOConnell and Creator/JohnRhysDavies each received a story credit on ''Series/{{Sliders}}'' - O'Connell got a few such credits (such as on "Way Out West") while Rhys-Davies only got it for "The Exodus, Part 1." In the latter case, it was the culmination of [[CreativeDifferences his feud with the producers and network]]: they purchased an outline he pitched as an example of how the show could better use its potential, drastically rewrote it into the kind of embarrassing B-movie he'd been complaining about, and [[spoiler:since he had just been fired for his outspokenness, [[McLeaned reduced his character to a mumbling brain-damaged state, fatally shot him in the heart, and left his corpse behind on a radioactive planet...]] ''[[ThereIsNoKillLikeOverkill which immediately exploded.]]'']]

* ''Series/DoctorWho'':

** Creator/JohnBarrowman, who played the initial BigBad and later HeelFaceRevolvingDoor character Malcolm Merlyn in ''Series/{{Arrow}}'', wrote ''Dark Archer'', a spin-off comic starring Malcom, with his sister Carole Barrowman.

* In 1955, ''Radio/TheArchers'' had an episode where Grace Archer, the wife of Phil, was killed off. (It may or may not have been a coincidence that the episode went out on BBC radio the very night [[Creator/{{ITV}} commercial television]] began.) The script had Grace's fate be conveyed in the final line of dialogue thus: "She... she died in my arms... on the way to hospital," but Norman Painting, who played Phil, suggested the line go "In my arms... on the way to hospital... she's dead!" Suffice to say that not only was this one of the most talked-about episodes of the soap, but Painting went on to write many, many episodes (and the book ''Forever Ambridge � 25 Years of The Archers''), as well as act in them.

* Most of the episodes of ''Radio/TheMenFromTheMinistry'' were co-written by John Graham, who also played most of the side-characters such as Lord Stilton and Mr. Crawley.

* Franchise/{{Arrowverse}}:

** Creator/NicoleMaines, who playes Dreamer in ''Series/{{Supergirl}}'', wrote a Dreamer story for the 2021 ''DC Pride'' special, the [[CanonImmigrant first appearance]] of Nia in comics.
* Other adaptations of Franchise/TheDCU:

** Creator/HelenSlater, who played the title character in the ''Film/{{Supergirl}}'' movie, wrote a story in the MilestoneCelebration ''Comicbook/Supergirl2005'' #50.

** Armin Shimmerman, who played Quark in ''Deep Space Nine'', co-wrote ''The 34th Rule'' with David R. George III. In addition to starring Quark, it cameos a number of other Ferengi Shimmerman played over the course of TNG, with Quark insisting they only look alike to ''hew-mons''.

* ''Franchise/STarTrek'':

* Creator/JohnDeLancie wrote "The Gift," an annual of DC's ''Series/StarTrekTheNextGeneration'' comic, focusing (of course) on Picard and Q.

* Creator/JohnDeLancie wrote "The Gift," an annual of DC's ''Series/StarTrekTheNextGeneration'' comic, focusing (of course) on Picard and Q.
* Franchise/{{Whoniverse}}:

** Franchise/{{Whoniverse}}:
* Creator/ColinBaker wrote ''Franchise/DoctorWho: The Age of Chaos'', a graphic novella featuring his Sixth Doctor, which is also something of a FixFic for [[spoiler:Peri's EsotericHappyEnding]].
* A number of ''Series/{{Torchwood}}'' spin-off comics were written by Creator/JohnBarrowman, who played the series protagonist Captain Jack Harkness, in collaboration with his sister Carole Barrowman.

** Creator/JohnBarrowman, who played the initial BigBand and later HeelFaceRevolvingDoor character Malcolm Merlyn in ''Series/{{Arrow}}'', wrote ''Dark Archer'', a spin-off comic starring Malcom, with his sister Carole Barrowman.

* The Barrowman siblings also wrote ''Dark Archer'', an ''Series/{{Arrow}}'' spin-off comic starring Malcom Merlyn, the character John plays in the series.
* Creator/ColinBaker wrote ''Franchise/DoctorWho: The Age of Chaos'', a graphic novella featuring his Sixth Doctor, which is also something of a FixFic for [[spoiler:Peri's EsotericHappyEnding]].
* The backmatter of the ''Comicbook/{{Stargirl}} Spring Break Special'' includes a series of excuses Courtney gave when skipping class to do superhero stuff, written by Creator/BrecBassinger, who plays the title character in the ''Series/{{Stargirl}}'' TV series.
* Creator/CamrusJohnson, who plays Luke Fox in ''Series/{{Batwoman}}'', wrote a Batwing story for ''Batman: Urban Legends'' #4. The issue was released the same day that the ''Batwoman'' episode where he dons the Batwing suit was broadcast.
* Creator/HelenSlater, who played the title character in the ''Film/{{Supergirl}}'' movie, wrote a story in the MilestoneCelebration ''Comicbook/Supergirl2005'' #50.
* Several stories in the comic book tie-in to ''Podcast/BatmanTheAudioAdventures'' have been written by members of the cast.
* Creator/DannyDeVito wrote a Penguin story for ''Gotham City Villains Anniversary Giant'', having played Cobblepot back in ''Film/BatmanReturns''.
* Creator/GilbertGottfried, who played a villain named Nick Nack in the ''Series/TheAdventuresOfSuperboy'' TV series, wrote an issue of the tie-in comic detailing the character's origin story.
* Creator/NicoleMaines, who playes Dreamer in ''Series/{{Supergirl}}'', wrote a Dreamer story for the 2021 ''DC Pride'' special, the [[CanonImmigrant first appearance]] of Nia in comics.

* Paul Darrow, who played Avon in ''Series/BlakesSeven'', wrote an officially-licensed spin-off novel, ''Avon: A Terrible Aspect'', which gives his own preferred version of his character's [[OriginsEpisode pre-show backstory]].

Key to both of these tropes is that the actor gets into writing or directing through the show they're on, '''without''' having a previous background in it (let alone being the series creator). For the opposite direction of crossover, see DescendedCreator and CreatorCameo. For shows where the cast and the writing staff heavily overlap, see CastFullOfWriters.

* Creator/LeighWhannell co-wrote ''Film/SawI'', and co-starred as Adam Faulkner-Stanheight.