These are the top ten film franchises that I would recommend for movie marathons (in no particular order)! Let me know your favourite franchise and your favourite movie in the comments below.
1. Harry Potter
This franchise specificity has a total of eight films to complete the series. A new addition to the Universe is the Fantastic Beasts movies which currently have only two films: Fantastic Beasts and Where To Find Them (2016) and Fantastic Beasts: The Crimes of Grindelwald.
2. Lord of the Rings
The Lord of the Rings franchise contains a series of three films. A further trilogy was produced later off the back of these films called ‘The Hobbit’ (a prequel to The Lord of The Rings) and could be included in a movie marathon. This would give the marathon  a total watch time of roughly 19.5 hours!
3. Star Wars
This franchise now contains a total of 10 movies with more upcoming in the pipeline. This includes two ‘spin-offs’, Rogue One: A Star Wars Story (2016) and Solo: A Star Wars Story (2018), as well as a sequel trilogy and prequel trilogy to the original three films.
4. Star Trek
This franchise now contains 13 movies: six in the original saga; four in the next series and then a reboot included Star Trek (2009), Star Trek Into Darkness (2013) and Star Trek Beyond (2016).
5. Marvel Cinematic Universe
This franchise currently has 20 films including within it and a 21st joining the series imminently in the form of ‘Captain Marvel’. There are of course various other films joining the series over the upcoming years such as another ‘Avengers’ sequel and a sequel to the Spiderman reboot.
6. Disney Pixar Animations 
The movies I would consider to be in this selection and suggest for a marathon are: Toy Story (1995); A Bug’s Life (1998); Toy Story 2 (1999); Monsters, Inc. (2001); Finding Nemo (2003); The Incredibles (2004); Cars (2006); Ratatouille (2007); WALL-E (2008); Up (2009); Toy Story 3 (2010); Cars 2 (2011); Brave (2012); Monsters University (2013); Inside Out (2015); The Good Dinosaur (2015); Finding Dory (2016); Cars 3 (2017); Coco (2017) and The Incredibles 2 (2018).
7. Jurassic Park/Jurassic World
This franchise is made up of an initial trilogy: Jurassic Park (1993); The Lost World: Jurassic Park (1997) and Jurassic Park III (2001). The films have recently been rebooted in a sequel-style form to create Jurassic World (2015) and Jurassic World: Fallen Kingdom (2018). A third film is expected to join the reboot to form a new trilogy.
8. X-Men/Deadpool
There are a total of 11 films in this movie franchise: six in the original series; three Wolverine spin offs and two additional Deadpool films. Although created by Marvel, I would see this series as separate to the Marvel Cinematic Universe and therefore suggest a separate marathon for these films.
9. James Bond
There are now 24 James Bond films in this huge franchise which has been around since the making of ‘Dr. No’ in 1962. The most recent film, ‘Spectre’ arrived at screens in 2015 and a new release is expected in the next few years. This comes alongside much talk about whether Daniel Craig (the current James Bond pictured above) will remain in his role or someone new will take over.
10. Indiana Jones
This franchise includes four films: Raiders of the Lost Ark (1981); Indiana Jones and the Temple of Doom (1984); Indiana Jones and the Last Crusade (1989) and the reboot of the series Indiana Jones and the Kingdom of the Crystal Skull (2008).
Genuinely Meg 