Archie Comics even had its own Expies of Archie, including That Wilkin Boy and Wilbur.
Fast Willie Jackson was an African-American Archie Expy from Fitzgerald Publishing.
Atlas/Seaboard comics published Vicki circa 1975... a feature that itself consisted of slightly-updated reprints of another Archie expy, Tippy Teen, which had been published by Tower Comics in the '60s.
Archie is also an Expy himself, being heavily-based off of Andy Hardy, a popular character played by Mickey Rooney at the time.
The Colleen Coover character Bandette was inspired by the French costumed heroine Fantômette, sporting an extremely similar costume.
Number 13, a strip about a supernatural family of monsters in the Anthology ComicThe Beano was The Munsters. Also Kat and Kanary is Sylvester and Tweety from Looney Tunes. The character Joe Jitsu from the 00s seems to be an expy of an earlier character entitled Karate Sid from the 80s.
Diabolik had a major series of expies. Interestingly, these expies lost their readers and ended publication by staying true to Diabolik's initial noir while Diabolik and the only surviving expy (Paperinik) moved to other genres (Diabolik to crime fiction and Paperinik to superhero).
Lee, the main character of Peter David's Fallen Angel is an Expy of Linda Danvers, protagonist of David's previous run on Supergirl. In fact, David did his best to fuel speculation that the characters were one and the same until the book's second volume, in which he chronicled Lee's origins. Later on, he introduced Lin, yet another expy of Linda Danvers, who can in fact be considered Linda in everything but name. Likewise, the God figure in the series is a small girl dressed in a tennis motif and carrying a tennis racket, which makes her an expy of Wally, the god figure in David's Supergirl who was a young boy who carried a baseball bat.
Jaeger Ayres, the protagonist of many of the arcs of Finder is an obvious Expy of Wolverine, being a short, tough, hairy guy who has a Healing Factor, suffers from occasional beserker fits, and has a tendency to non-creepily befriend teenage girls.
John Byrne's college newspaper strip Gay Guy! had a villain called Charisma, whom no man could resist except... well, guess. Byrne liked the character concept so much that Karisma showed up on the Fantastic Four's doorstep a decade and a half later.
Hellboy fought against a vampire lord named Vladimir Giurescu that was obviously modeled after Dracula, sharing traits such as having many vampire brides and a similar appearance to his real life inspiration. What is more is that before his plans were ruined by Witchfinder Edward Grey, Giurescu sought to install his own secret domain in Great Britain during the 1880s (more or less the same goal as Dracula and in the same time frame where the novel took place).
An oft-mocked facet of early Image Comics was that every team seemed to have a Wolverine expy, who had blades on his hands, a bad attitude, and a mysterious past. And while it wasn't every team – Gen¹³ and Stormwatch being the most notable exceptions – this was true for most of them: Youngblood (Image Comics) had Troll and Cougar (though the latter was arguably more influenced by Beast), while spin-off series Bloodpool had Wylder; Cyberforce had Ripclaw; Wild CATS Wild Storm had Warblade; Bloodstrike had Deadlock; and Codename: Strykeforce had Killrazor. Deadlock was probably the most obvious, since his first costume featured a mask nearly identical to Wolverine's.
One story in The Maze Agency featured a detective named Senor Lobo, whom writer Mike Barr has acknowledged was a deliberate homage to Hercule Poirot.
The title character of Tekno Comix's Mickey Spillaine's Mike Danger is very explicitly Mike Hammer under a different name — according to the book's writer, Max Allan Collins, the name Spillaine originally intended him to have — and then Human Popsicled into the future. This is straight-up stated in the text piece at the back of the first issue.
Thunderbolt is both a version of an established character and an expy of Watchmen's Ozymandias, who was himself a Captain Ersatz of the original Thunderbolt, making him… a recursive bifurcating expy?
The other superheroes from Cannon’s world might be identified as very loose expies or Captain Ersatz figures for well-known Marvel or DC supers, but Nucleon in particular has a little in common with Watchmen's Doctor Manhattan. Then, when she arrives in Thunderbolt’s world, her powers shift to make her more like him — because that world’s (deceased) Nucleon was clearly more of a Manhattan expy.
Some of the regulars in the pub on the black-and-white non-supers world share first names and a few personal characteristics with the main cast of Watchmen, making them perhaps as near to expies as you can get in a pub on a world without superheroes.
Detective Gould from Matt Kindt's Red Handed is an expy of Dick Tracy. He wears a very similar suit and hat, has an array of retro-futuristic gizmos, and is named after Tracy creator Chester Gould.
Mammoth Mogul borrows quite a bit from Vandal Savage. Like Vandal, Mammoth was originally from prehistoric times before being exposed to strange energies rendering him immortal. Despite their primitive origins, both like to dress fancy and appear cultured. They both also seek world domination.
Doctor Finitevus, an obvious Expy of Doctor Zachary from Sonic the Comic. Let's see. Is a villainous albino? Check. Has the "doctor" title attached to his name? Check. Is an echidna and one of Knuckles' people? Check. Has a fixation with Chaos Energy? Check. Has manipulated Knuckles (either by exploiting his character, or via brainwashing)? Check. Has had a powerful minion who was empowered by Chaos Energy? Check.
Supreme from Image Comics is an Expy of Superman, obviously. Originally this was mainly in terms of power set and appearance – in personality and outlook on the world, though, Supreme and Superman couldn't have been more different. When Alan Moore took over the series, his in-universe Continuity Reboot made the comparison much more explicit.
From the pre-Moore era, Kid Supreme was a fairly direct take-off of Kon-El from DC Comics, with almost the exact same appearance and personality. His short-lived solo series, however, owed a lot more to the contemporaneous Robin and Impulse series in its tone and status quo.* Being highly influential and popular, Tintin spawned many expies in Franco-Belgian Comics:
Marc Dacier is also a reporter going around the world like Tintin. He solve mysteries and foil criminals of all kind. He's also has high moral standards and believe in doing the right thing above else. Unlike Tintin however, Dacier is seen doing his job as a reporter.
The Lefranc series recount the adventures of Guy Lefranc, a reporter for a newspaper. Like Tintin, he goes on various adventures and face off against terrorists, remnant Nazis, greedy businessmen.Very much like Tintin, Lefranc doesn't have much flaws and is a humanist.
Riptide's father Storybook Smith is based off the Golden Age hero Johnny Thunder, with whom he shares Reality Warper abilities and a fondness for tacky green checkered suits.
The Fighting American was an expy of Captain America created by Cap's original creative team of Joe Simon and Jack Kirby. Rob Liefeld's attempted revival of the character in the 90s dialed up the similarities, so much so that Marvel eventually took legal action against him.
Oddly enough, he received his own expy in the form of the Fighting Yank during his AC Comics series. The Fighting Yank was redesigned and given a costume almost identical to that of the Fighting American.
Even more oddly, Captain America himself is an Expy of a now obscure character, The Shield, also developed by Jack Kirby and Joe Simon.
Commander Steel from All-Star Squadron was another Captain America Expy. Justice League lampshaded this by having the second Steel mimic Cap's iconic shield throw.
In 1936, Jerry Seigel and Joe Shuster created Dr Mystic, an Occult Detective who was given a mission by a mystic council called the Seven, via an intemediary named Zador, for The Comic Magazine #1, published by Centaur Comics. The character was so blatantly Dr Occult (created by Seigel and Shuster for National Publications' More Fun Comics the previous year) that they continued the story in More Fun, and didn't even change the Seven or Zador's names!
The F1rst Hero: The extrahuman group introduced in Issue #3 is lead by a fat black man who calls himself Fat Alvin.