A serial which, by design, does not run regularly. It may be a series of annual made-for-TV movies, or a series composed of miniseries airing every few years but lacking the regularity of a Television Serial. Often happens when a Pilot Movie sparks enough interest to prompt a second movie, but not enough to prompt a regular series.
In the US, these are typically revivals of series that were originally regular in format. They are far more common in the UK. British Irregular Series are often aired on public television in the US as part of a Genre Anthology such as Mystery or Masterpiece Theatre.
Irregular updating characterizes the majority of Fan Works because the authors do it for fun and don't profit from their work.
Might be the result of increasingly frequent Schedule Slips. Compare Series Hiatus (a work stops updating without being officially cancelled) and Inconsistent Episode Lengths (for when the length of each episode is what's irregular, rather than the publication schedule).
Examples:
By Creator:
- Kaoru Mori's first officially published manga Shirley went on to become a project on the side of her regular comics, with new chapters being published extremely irregularly. As of the currently latest published chapter from 2023, 19 chapters have been published over the course of 23 years. Reading the whole series from the start truly shows off Mori's Art Evolution.
- Rumiko Takahashi's Mermaid Saga, a manga variation of this, was periodically released in episodic stories over the course of ten years.
By Work:
- Lupin III has made six regular anime series, but has run for over twenty years as an annual series of made for TV movies in Japan. Link to the list: Lupin III Yearly Specials
- Thus Spoke Kishibe Rohan has no set schedule, with gaps between installments ranging from one month to over a decade.
- Big Finish Doctor Who: At least while the Main Range was being released, story arcs for each Doctor would often be interspersed with trilogies which went in an entirely different direction. To give one example, the Seventh Doctor/Ace/Hex arc was covered in a trilogy released in mid-2009. The Cliffhanger in the last story wasn't immediately followed up on, because in early 2010, a trilogy featuring Elizabeth Klein was released. The next Seven/Ace/Hex trilogy was released in late 2010, and because 2011's trilogy, in the middle of the year, saw the Doctor travelling alone, listeners had to wait until mid-2012 for a continuation. The even more dramatic cliffhanger of this trilogy was addressed in a single story in December 2013, as in the interim, another trilogy featuring Seven and Klein, joined by new companion Will Arrowsmith, was released. Finally, in late 2014, one last trilogy concluded Hex's story. Got all that?
By Creator:
- IDW Publishing: For its first few years, the publishing house's Transformers series consisted of multiple mini-series and a 12-issue event series before receiving an ongoing.
By Work:
- Paradoxus: First posted in 2014, it has never had a proper update schedule, with chapter releases ranging from some weeks to several months apart. The retooling has not helped in terms of consistency. Yet, even after more than a decade, Bloom_Farella keeps releasing new chapters.
- A Wizard's Guide to 'Banking' was first published on January 18th, 2017. Updates could take weeks or months, and there was a Series Hiatus lasting from April 2022 to February 2025, when the author picked up again.
- Three Sheets to the Wind: Technically speaking, Three Sheets to the Wind isn't officially over, but it's not considered ongoing either. It's always been a loose, unscheduled project, so even if Coeur Al'Aran hasn't updated it since November 26, 2022, he could easily post a new chapter at any time. In the notes to chapter 2, he also explains that a Crack Fic can only do so many jokes before it stagnates, so if he keeps posting more chapters, Jaune's alcoholism will get to the point of becoming really disturbing and the fanfic will lose its charm.
- 【Amaranthine Shadows】: Right off the bat, Lila Gaela warned her readers not to expect any kind of regular updating other than the chapter batch she uploaded all at once. Worse yet, she posted the story's prologue several days after the first chapter and then re-uploaded that first chapter as the actual third one, adding some more plot in between.
- Dragon's Daughters: Ever since Bloom_Farella first published it on April 2017 up to its last update on May 2021, it's never followed any sort of schedule. While it's true that the bulk of it saw constant updates, these slowly petered out with longer and longer hiatuses between chapters until the author stopped altogether.
Other
- SeerKing adheres to a "writing schedule" on what they will write next, but they will occasionally write or update fics outside of the schedule if they so desire. This can cause fics outside of the schedule to go years without updates. While only fics without personalized covers are ever outright declared dead, several fics with covers yet not part of the schedule are effectively dead in all but name, such as "Code Geass: Numbers Reshuffled" and "Ranma Saotome, Chi Master". This is mostly thanks to the many Plot Bunnies that plague [=Seer King=}.
- Adam Dalgliesh: The Roy Marsden adaptations consisted of TV movies and mini-series, with releases spanning from 1983 to 1998.
- Big Fat Quiz of the Year: Unlike regular panel shows, this one is a yearly feature-length special that airs around Christmastime. Big Fat Quizzes with other topics (BFQ of Everything, decade-themed quizzes) vary from year to year with no set release schedule.
- Columbo started life as a Made-for-TV Movie, then became a series which aired as every third episode of The NBC Mystery Movie. Later, it became a series of TV Movies that aired with decreasing frequency.
- Foyle's War: The series that was produced following the show's un-cancellation became more noticeably irregular in their release, with gaps of 2-3 years between series.
- Furuhata Ninzaburō: The series aired between 1994 and 2006 and produced four seasons and 42 episodes (thirty-two 45-minute episodes and 10 feature-length ones) with no set schedule.
- Hetty Wainthropp Investigates: The pilot aired in 1990, whereas the four series aired in 1996-98.
- The Incredible Hulk (1977): A four-year regular series sandwiched between two pilot movies and three made-for-TV-movies.
- Inspector Morse aired as a number of Mini Series but became this after the seventh series, running four one-off episodes over the next six years.
- Jonathan Creek aired as a combination of specials and series, most notably with three specials released during 2009-2013, which came between the fourth (2003-2004) and fifth (2014) full series of the show.
- Marple: Each of the six series, aired between 2004 and 2013, contains 3-4 feature-length episodes.
- Mr. Bean, with the exception of the first 6 episodes which aired weekly, the series aired sparsely from 1992 to 1995.
- Perry Mason ran regularly from 1957-1966, then was revived for a series of TV movies in the 90s.
- Poirot:
- It initially ran from 1989 to 1993, then became a series of feature-length specials whose releases spanned almost two decades.
- The format switched to "series of TV movies" in 2009 to allow the actors to follow up on other commitments that a full-scale TV schedule would conflict with.
- Prime Suspect aired one series per year from 1991-96 (skipping 1994) then the final two series aired in 2003 and 2006, respectively.
- Psych became one following its original eight-season run, as installments thereafter are made-for-TV movies.
- The Rockford Files became a series of TV Film for a time after the regular series ended.
- Rumpole of the Bailey released intermittently from 1978 to 1992.
- Sharpe ran with a really noticeable time skip between the most recent installments.
- Sherlock consists of four three-episode series, with a two-year gap (or three, in the case of the fourth series) between them.
- Tatort: 1971 saw 11 episodes of the series, 2008 saw 31, and not evenly distributed to boot. In the first twenty years, the length of episodes varied, too, up to two hours; more recently things settled on about one and a half hours.
- The Thick of It: The first two series aired in 2005, followed by specials in 2007, a third series in 2009, then a fourth and final series in 2012.
- Up takes this to extremes by airing a single instalment every seven years. It started by showing the participants at seven years old and has gradually charted their lives in seven-year intervals ever since.
- Talkernate History: Even with months-old gaps between episodes, the series had uploaded steadily for more than a decade.
- Boomer's Big Date: After the conclusion of the story's main plot (Miles and Boomer getting together) in "Test", Nanoff stopped updating weekly, favoring non-scheduled releases of Slice of Life one-shots.
- Terrible Writing Advice: Although the series used to have a bi-weekly uploading schedule, there were a few Schedule Slips and now the uploading schedule is irregular, uploading nearly once a month with the occasional double-upload. He went on to spend practically all of 2024 without uploading any episode, only breaking the hiatus in December, clarifying that he did so to avoid burnout and work on his writing.
