The shorts "Dial M for Monkey" and "The Justice Friends" are just as popular if not more so than the main Dexter shorts, in a better case, the latter.
Huntor, the villain of the "Dial M for Monkey" short of the same name. Surprisingly, his design was well-liked enough to earn him a cameo in Samurai Jack, to the point of him becoming the "bounty hunter" template for Battle Through Time.
Lisa the babysitter. She only appears in a very early episode of the series and never shows up again after that. But look up any fanart of her and you'd be surprised at how much of it there is. Guesswhy.
For similar reasons, The Touchy-Feely Neighbor Lady, Midge the waitress and Candi, the Dee Dee replacement, are widely remembered despite only appearing in one episode each.
Mandark's abrasive younger sister and Dee Dee's rival-turned-friend Lalavava only appeared in one episode, yet has a substantial amount of fanart, enough to have gained her own category in some fandom groups for the show.
Lee Lee, one of Dee Dee's friends, is one of these as of late.
Douglas Mordecai III, Dexter's best friend, despite being a borderline Satellite Character. He is popular because he's the only character Dexter could talk to like a human being.
Valhallen has a ton of fangirls.
The Puppet Pals. Some people wished they had their own Spin-Off (the closest we got were some live-action segments featuring the duo to fill time in some eps).
The robot parrot from "The Parrot Trap", thanks to its statements making the episode one of the funniest in the show's history.
Creepy Eyed Girl is a major fan-favorite thanks to how Creepy Cute she is, as well as her downright endearing crush on Dexter.
