The cover of Uncanny X-Men #136 (Cyclops holding Phoenix) may have been inspired by an older work of art, but it is sufficiently different from Michelangelo's Pietās to be considered in a different category from them. (For starters, Cyclops is standing, not sitting). And the Pietā representation of Mary and Jesus had itself been used by plenty of sculptors for 150 years before Michelangelo was even born, to say nothing of not dissimilar artistic representations of other mothers with dead children dating back to pre-Christian times (e. g. Eos and her son Memnon, Niobe and one of her daughters).
Wizard magazine, the most "mainstream" magazine on comic books, once contemptuously referred to the immortal supervillain Vandal Savage as "a cheap Ra's al Ghul knockoff". Actually, Vandal Savage predates Ra's by twenty eight years — 1943 and 1971, specifically.
Ming the Merciless has been referred to as "a cheap Ra's al Ghul clone" as well. Ra's and Ming are, of course, knockoffs of Fu Manchu, who wasn't the first Yellow Peril villain either.
It's a meme among Fantastic Four fandom that Trelane from the Star Trek: The Original Series episode "The Squire of Gothos" was ripped off from FF villain Infant Terrible, apparently for no more reason than being child-like and omnipotent, despite the fact that there are literally hundreds of examples of this combination going back at least to the 1920s.
Many people seem to think that Aquaman came before Namor the Sub-Mariner, even though Namor predated him by two years. This may be because Namor went out of print during The Interregnum, while Aquaman held on as an Action Comics backup.
The DC Comics skull-faced supervillain Doctor Destiny is often called a knockoff of Skeletor, despite the fact that he predates him by several decades. It is also important to note that, besides appearance and the fact that they're both villains, these two characters have absolutely nothing in common. And a skull face is not exactly a new or unique concept to start with.
a man "of iron" with skin so tough that it can withstand anything short of an exploding artillery shell;
able to jump so high it's like he's flying;
imbued with a high morality and sense of justice;
who hides his true ability from everyone;
fights a wrestler for money;
singlehandedly builds a fortress in a wilderness;
has adventures where lifts a car, and rips the door off a bank vault...
The character is Hugo Danner, Gladiator, from a book published in 1930, before Superman or Spider-Man. Siegel & Schuster have admitted to taking inspiration from it when they created Superman.
Even better, Marvel later created a character named Gladiator as a Captain Ersatz of Superman for their own universe, bringing it full circle. Read more about that here: [1]
DC, which published a few stories of the original Hugo Danner (as did Marvel), gave Danner a son named "Iron" Munroe who filled in for Golden Age Superman in the Retcon patchwork that The DCU's World War II history became Post Crisis, when many of the formerly Golden Age heroes were given new, recent origins. Now, the adventures that happened to Superman During The War, mostly happened to Munroe instead.
Shuma-Gorath predates his appearances in the Doctor Strange and Conan the Barbarian comics, all the way back to a mention in one of Robert E. Howard's Kull stories. The story was published in the 1960s, but could not have been written later than the mid-30s, making this character Older Than Television. This is also a case of Adaptation Displacement.
"Deathstroke the Terminator" appears first in a Marvel comic book; Spider-Woman, during the early 1980's. He's the leader of some ninja-likes, the Terminators (who are not cyborgs from the future).
A number of comic book fans commented that the spaceship◊ in the European comic book Valerian was totally plagiarized from the Millenium Falcon. Except Valerian and his ship were created in 1967, and Star Wars was made in 1977.
Others commented that the flying cars seen in one of the Valerian stories were totally plagiarized on The Fifth Element — forgetting that the idea of flying cars has been around since... well, the invention of the car. Not to mention that the story was published years before the movie was made, and that the director is a Valerian fan who specifically asked the series' artist to work on the design of the movie.
Some have claimed Watchmen's ending, in which the world unites against an alien threat after New York City is destroyed, is an attempt to capitalize on post-9/11 feelings. However, not only does Watchmen predate 9/11 by 15 years, but the eerie similarities between 9/11 and Watchmen's climax have been noted by more than a few people, especially in regards to whether Ozymandias' plan to bring about world peace would work even temporarily in real life given that world sympathy for the United States was temporary and only lasted until the United States invaded Iraq.
Not to mention the ending is very similar to The Outer Limits episode "The Architects of Fear". This is acknowledged in the ending (it's the episode playing on Sally Juspeczyk's TV).
An in-universe example has Superboy saying to Superman "Second star to the right and fly till morning." When Superman says "Peter Pan. How appropriate." Superboy replies "What are you talking about? Captain Kirk said that." in reference to Kirk's closing line at the end of Star Trek VI where he was clearly quoting Peter Pan.
After the fairly obscure character The Question became the Ensemble Darkhorse of Justice League Unlimited, many people declared him to be a rip off of Rorschach. In fact, Alan Moore only created Rorschach because he was told he couldn't use The Question, the character he had originally planned to use in Watchmen.
Many fans of misfit superhero teams who are hated and feared by the public they protect and are led by charismatic wheelchair-bound men often think that DC's Doom Patrol is a blatant ripoff of Marvel's more popular X-Men. Other comics fans who know a little more about the books' histories know Doom Patrol was actually published first, and assume the theft went the other way around. In fact X-Men followed Doom Patrol by only three months, and given the lead time involved in the production of comics it's most likely no plagiarism was involved. However, some artists and writers worked clandestinely for both companies, and it is possible that information flowed one way or the other.
Well, when one property's Rogues Gallery is The Brotherhood of Evil and the other's The Brotherhood of Evil Mutants, it's pretty obvious SOMEONE was reusing ideas.
Except that both Brotherhoods debuted at the exact same time. Both showed up in March of 1964. Yep. Same month of the same year. Making it pretty damn hard for either to be a rip-off.
Stan Lee spoke at the promotion of his "add a caption to a photo" book in 2009. In it, he specifically said that he created the X-Men because his publisher (maybe wrong title) wanted something to compete with Doom Patrol. (Lee wanted to call the book "The Mutants," but his boss over-ruled him.)
Lee himself has admitted that he has a poor memory, so it is possible that he is misremembering. It is all but impossible for the X-Men to have been inspired by Doom Patrol, as it usually took over six months to develop a comic in the 60's. As mentioned above, there were three months between the two teams respective debuts, which would mean that the X-Men would have already been in the works when Doom Patrol hit the stands.
The mix of ancient characters with original creations in stories about characters like Marvel's Thor and Hercules and DC's Wonder Woman leads to an understandable amount of both Older Than They Think and Newer Than They Think. Notable examples include reviewers thinking a character was being antisemitic for calling Hercules's wife "Hebe" (that's her name, from classical Greek mythology).
Brian Azzarello's wildly popular Batman story, entitled Joker about (you guessed it) the Joker takes place in a more realistic universe, where the Joker is depicted as a more believable psychopath. His long messy hair, splotchy "makeup", and Glasgow smile made him a very unique version of the character.... until The Dark Knight came out. Many people after that, thought that the comic "ripped off" Heath Ledger's Joker or that the story is meant to tie in with the film. However, this was just a coincidence, they had already started the story before they even saw what Ledger looked like.
The comparison is only appearance based however as Ledger's Joker and Azzarello's Joker have very different personalities.
We first went to the moon in 1969. Snoopy was there earlier that year. Tintin predates Snoopy by 16 years, going to the moon in 1953. Donald Duck already went there in 1948. But of course, Jules Verne's Around The Moon predates everyone, being published in 1870. That's 99 years before Real Life. Note that in From The Earth To The Moon nobody set foot on the moon.
James A. Owen received a lot of hate mail for "stealing" the characters of Titania and Oberon from Neil Gaimen's Sandman series for his own Starchild series. It got so bad that, as a favor, Neil wrote the intro for the collected anthology explaining that James did not, in fact steal anything that wasn't already stolen.
Some fans have accused Spider-Man archenemy Norman Osborn (aka the Green Goblin) of being a rip off of Lex Luthor, because both are Corrupt Corporate Executives. Thing is, Norman's been an evil businessman since he debuted in 1966 (his Goblin alter ego debuted two years before he did interestingly enough), while Luthor was a traditional Mad Scientist from his appearance in 1940 until his reinvention as a businessman in 1986.
