Other than the main cast, some characters had received a cult following by their themes, actions, etc.
- Out of all the Recolors, X and FM are the most beloved. This is because they are pretty much the only Recolors to be recurring characters still after SMG4 stopped using Recolors in major roles in the mid-2010s. They have had a large number of major roles in more modern SMG4 videos (Two Great Friends!, Seaside Stupidity and the 10 Year Anniversary Movie to name a few) and have recognizable personalities that make them loved by the fandom. Their resurgence in appearances starting in 2021, coinciding with their real-life selves becoming involved with the series againnote , was well-received.
- SuperLuigiGlitchy4, SMG4's brother from the episode "sup' bro" has gained somewhat of a fanbase, appearing in fanart despite having since vanished since his debut and Word of God confirming during a Mail Time video that he was indeed Killed Off for Real at the end of his debut appearance. Helping is Weegeepie adopting the character on his channel.
- Old Man Hobo for being a crazy Cool Old Guy and one of the earliest gag characters.
- Slenderman for his Odd Friendship with Mario. He still makes appearances now and then.
- McShyGuy, better known as Toast Guy, for his extreme love of toast.
- Chica for her love of pizza to the point where she became a recurring character after the first FNAF video.
- The TF2 Mercs for their general insanity and for having some of the most loved voice clips.
- Minion from "Luigi's Labyrinth" is very well-liked by the fanbase due to her Adorkable nature.
- Grand Dad from "THE BOOTLEG DIMENSION". Most will agree that he's a surprisingly Tragic Villain in contrast to SMG4's other antagonists, who are usually comedic goofballs or evil forces of nature.
- McCree for his bizarre personality and extensive sentence mixing. He was briefly a recurring character in 2017.
- Beta Luigi from "AREA 64" was popular enough to get second place on a YouTube poll for the favorite secondary character, beating out Bob, Shroomy, and even Meggy, only losing to Fishy Boopkins, despite being added onto the list as a joke, perhaps in part due to his truly tragic Heroic Sacrifice.
- Quite a few fans took a liking to Shroomy thanks to him being an awesome Boy Scout and his unique design.
- Chris and Swagmaster69696969696 are some of the most popular, yet at the same time rarest, characters in the SMG4 cast, and it's not uncommon to find comments requesting more videos with them, making it all the more triumphant when Chris and Swag got promoted appear in the show proper.
- Mario's descendant in "The Weegee Uprising", New Super Duper Mario Plus Ultra, became one for his surprising planning skills and, like fellow darkhorse Beta Luigi, pulling off a Heroic Sacrifice so Luigi, Boopkins, and Shroomy could Set Right What Once Went Wrong.
- Rob from "π½π½π½π½ππΈπ»π·π½π½π½π½" is also a fan favorite, mainly due to his hilarious lines. His budding friendship with Bob, especially in "The Corn Trip", also helped.
- In a roundabout kind of way, Desti. Despite appearing in a single arc as Meggy's rival before she gets Killed Off for Real by Francis, her profound impact on the series' characters and its status quo, in general, elevated her as one of the most memorable characters, even acknowledged by Luke and Kevin themselves on multiple occasions despite their firm stance to never bring her back to the series in some way.
- Similarly, the alternate Desti from the final segment of "WHAT IF...?" gained a fanbase for her good showing despite her short screentime, her badass outfit, her more built-up friendship with her Meggy before the latter's tragic death, and, of course, being a living alternate incarnation of an already fairly popular dead character. Some fans even felt she was a better character than her mainline counterpart for her expanded role and depth, and many fans voiced their desire to have her meet mainline Meggy or for her timeline to be explored more.
- Terrance, SMG3's pet Ugandan Knuckles that shows up in a few episodes—partly for being an adorable Morality Pet to SMG3, and especially for his shockingly sad Heroic Sacrifice in Revelations (to the point where when the movie first aired, the subreddit was filled with fans mourning his death despite there being many more dramatic moments that the movie focused on more).
- One-Shot Wren has quickly become considered one of, if not the best Arc Villain in the series due to how well-acted and genuinely unsettling the characters and their actions are.
