Scooby-Doo is filled with memorable monsters and people that become fan-favorites, despite being minor characters in the franchise overall.
- The Ghoul School Girls from Scooby-Doo and the Ghoul School. While the special was their only appearance in the franchise, they are fondly remembered by the fanbase thanks to their Cute Monster Girl designs and for being genuinely nice and friendly towards Scooby, Shaggy, and Scrappy. They eventually reappeared in an episode of OK K.O.! Let's Be Heroes 30 years later, with three of them having their original voice actresses.
- Scooby-Doo and Scrappy-Doo: Scrappy's friends, Duke and Annie. They appear in a single episode, but their terrific chemistry with Scrappy, their role as his close friends before he joined the gang, and their developed personalities make them quite memorable.
- Vincent Van Ghoul from The 13 Ghosts of Scooby-Doo. Being voiced by Vincent Price may have something to do with it, and it's most likely the reason why Van Ghoul returns in Scooby-Doo! Mystery Incorporated.
- Several of the monsters have become very popular, such as the Tar Monster and Captain Cutler, which is why they re-appeared in Monsters Unleashed.
- Another monster, the Creeper, is another fan favorite, to the point that it's appeared in later installments of the franchise, including Scooby-Doo and the Cyber Chase and Mystery Incorporated.
- The Luna Ghost from Scooby-Doo (2002) was seen as an effective Starter Villain for the movie with mannerisms that remind people of The Joker and Pennywise.
- Mary Jane from the same movie is considered by many as a great love interest for Shaggy, who is kind to anyone she sees and shares Shaggy's cravings for Scooby snacks.
- Melvin Doo from two scenes of Scooby-Doo. A joke character, sure, but it's a pretty funny joke.
- The Cotton Candy Glob from Scooby-Doo: Monsters Unleashed is a One-Scene Wonder simply because Shaggy and Scooby eat him up.
- The Tar Monster was surprisingly frightening to watch in Monsters Unleashed, which is why he became memorable for contemporary audiences.
- The 10,000 Volt Ghost from Monsters Unleashed is also well liked for the same reason as the Tar Monster, being a genuinely scary and dangerous villain while also invoking Evil Is Hammy in all of its glory.
