The Marrissaverse is a meta-location encompassing all locations of most MarissaTheWriter stories. To this date, Invader Zim: Born Again Christian, Post-SCrash Session 2: The Belorussian Aliens and Real Beauty are the only MarissaTheWriter stories that do not take place in this universe. In addition, in Additional Discoveries on Marrissaverse History, Skepness Man Beauregarde claims to have visited an universe different from the Marrissaverse, and ITS MY LIFE!, TEEN FORTRESS 2 and Portal: The 4th Millennium: The Trollfic Edition make mention of Andord Hell, also separate from the Marrissaverse.
The term "Marrissaverse" is typically not mentioned in MarissaTheWriter stories, barring the names of the stories Additional Discoveries on Marrissaverse History and Marrissaverse Stories 2015. However, the concept is frequently mentioned as such using the term (and/or its variants such as "MarrissaVerse" and "Marissaverse") by other people discussing MarissaTheWriter stories, even if the term is sometimes taken to mean "all stories written by MarissaTheWriter", rather than the meta-location.
The Marrissaverse's centerpiece is the Earth; most stories either deal with the Earth or citizens coming from it.
The Marrissaverse's citizens are depicted as having lower average intelligence than our universe's residents. Their language tends to have misspellings and inflected words. In addition, other sub-human species, such as falmer trollz, cherub trollz and powerful humans, inhabit the universe.
The inclusion of Invader Zim: Born Again Christian in the Marrissaverse is debated. Even though the story claims to be set in another continuity and features entirely different main characters and/or versions of characters of the Marrissaverse who have different biographies, Enchiridion Marrissa and Additional Discoveries classify the story as a part of the main Marrissaverse, as the era "Before Deschanel" (meaning that the two universes are not directly interconnected and one cannot be time-travelled to from the other, but they still share elements such as Portal High School).
- ITS MY LIFE! makes a mention of "the hole portal worled" as the meta-location, as it precedes the coinage of the term "Marrissaverse" (as there was only one story by MarrissaTheWriter at the time).
- Marrissa Picard appears to also be from a universe which could be called "the Marrissaverse", therefore causing confusion in use of the term in Marrissaverse Stories 2015.
- ITS MY LIFE! (First appearance)
- TEEN FORTRESS 2
- Portal: The 4th Millennium: The Trollfic Edition
- OMG IMMA IN LOFE WIDDEN ALEEYEN!
- THE MARRISSA GAMES
- Post-SCrash Session
- Enchiridion Marrissa
- Post-SCrash Session 3: Spectators of the Host
- Additional Discoveries on Marrissaverse History
- Living Someone Else's Life
- Dick Stiller and Roxa Lavigne's Time Travellegiance
- Post-SCrash Session 4: Parody of a Parade
- HARRY POTTER AN THE KILL OF SNAPE
- Marrissaverse Stories 2015
- The AG 1991 Premiere of Inside Out
- ITS MY LIFE!: THE FLAMES AWAKENS
- Meanie Pixies' Hour of Fame