Lord Zet and Nekoneko of the flash series Super Freakin Parody Rangers are deliberately obvious Expies of Zetto and Ruri from the creator's earlier work TTA.
Dr. James Zanasiu, main character of the Darwin's Soldiers RPs is an expy of James Miardian, the scientist from the first RP that James's creator ever played: The Spreading Hazard.
Dr. Bailey, who first appeared in the rebooted Furtopia RP, was an expy of Dr. Shelton from the Gang of Five RPs, after the latter showed how useful it was to have a non-action tech guy around.
A fair amount of characters from Survival of the Fittest. Occasionally, you will see one of a character from a previous version or the original canon (for example, Melina Frost was clearly at least to some extent inspired by Mariavel Varella of v2, and possibly by extension, Mitsuko from Battle Royale). Other times, you will see ones of characters from other works, based on people the handler knows, or are imported from other roleplays the handler has participated in.
Doctor Linksano from Atop the Fourth Wall is one for Doctor Insano from The Spoony Experiment. Justified in that Linkara created Linksano, because he felt bad about asking Spoony to play Insano for him over and over. And of course it's also lampshaded because he is Insano's counterpart from alternate reality.
In The Gungan Council, several characters use avatars from the Star Wars films, including C'oringath and Ceel. Others use avatars from the Expanded Universe. Usually, these characters even match their avatar's in personality.
Given the premise of the show, Coyle Command takes a lot of its characters from G.I. Joe. There is Coyle Commander (Cobra Commander), Anni (Destro), Countess Crossland (The Baroness), and COMMANDO (G.I. Joe itself)
She's still a three-dimensional character and takes inspirations from others too, but The Nostalgia Chick is fundamentally an older, more broken Daria.
The Saga of Pretzel Bob features as its villain a silver-haired man in a black cloak who sets the main character's hometown ablaze and wants to destroy the world... named Seraphoth.
Champion is clearly an expy of Superman, down to the freezing breath and the heat vision.
For that matter, Fantastico is an expy of Superboy, complete with the super-strength and the heat vision. Oh, and he might also be a pastiche of George W. Bush.
Dr. Yablonski is even lampshaded as basically being Batman as a physics teacher.
Aquerna has squirrel powers, including being able to talk to squirrels and command them. Who could that be?
