As two of the biggest comics companies, fans are used to relating their characters to Marvel and DC. If someone mentions Batman then the DC Logo immediately comes to mind. Talk about Wolverine and the Marvel Comics logo from the top left corner of the books will be sparked into fan memories. It might surprise people to learn that some of their popular characters didn't start within their hallowed halls.
Whether it is from a company purchasing another organization, a creator having the chance to take their characters elsewhere, or some weird circumstances that allowed it to happen, it can be jarring to learn that the DC or Marvel Universe isn't a famous character's first stop.
10 Plastic Man
Patrick 'Eel' O'Brien started his life out at Quality Comics. He began as a criminal who gets shot during a robbery and ends up exposed to some unidentified chemicals, which later gives him his stretchy abilities. After resting at a monastery to heal up he decides his abilities are better used to fight crime.
After Quality Comics folded in 1956 DC Comics bought a lot of their characters. Plastic Man got integrated into their universe. He eventually ended up in the Justice League where he usually plays the comic relief. Through his various comic titles, TV appearances, and animated film appearances most fans would for sure think he would be a DC original.
9 Prime
He doesn't make appearances anymore with Marvel seemingly not wanting to use any of the Ultraverse Characters due to what is believed to be copyright issues, at one time Prime was the face of Malibu's comic universe. After Marvel bought Malibu Comics they began to crossover the Ultraverse characters with the characters from Earth 616.
Prime ended up having a lot of adventures with Spider-Man, Thor, Hulk, and Captain America before the Ultraverse fell into obscurity. Many fans have been clamoring for a revival of these characters but Marvel doesn't seem to have much interest in ironing out the issues they believe are blocking the use of these characters.
8 Miracleman
Oh boy, so this one gets complicated. Originally known as Marvelman, he was created as a replacement by the UK publisher that ran the Fawcett titles like Captain Marvel. After the company's decision to end Captain Marvel, L. Miller & Son Ltd. decided to create their own character to replace him. This lasted until 1963 when the company went bankrupt.
In the 80s it was decided to bring the character back but Marvel threatened lawsuits over the name so it was changed to Miracleman. Eclipse ultimately ended up with the character but also folded in time. Neil Gaiman tried to secure the ownership rights to Miracleman, but Todd McFarlane ended up buying all of the Eclipse properties. He claimed ownership but the purchase was later found not to include the Miracleman IP. Marvel ended up with the character once again and began reprinting some older adventures. New stories written by Gaiman appeared before they abruptly stopped.
7 Captain Marvel/Shazam!
While he's now known as Shazam the big guy started his life out as Captain Marvel over at Fawcett Comics in 1939. After a while his adventures began to outsell Superman which made DC take notice. They filed a copyright infringement lawsuit against Fawcett claiming that he was just a copy of Superman. His books ceased publication in 1953 due to this and the character disappeared.
In 1972 Fawcett licensed him to DC for new stories but by 1991 DC would own all the characters from Fawcett anyway. During this time he and his Marvel Family were integrated into the DC Universe proper. He has been a popular character and was given his own live-action film in 2018 that tied into the DCEU. He briefly got to share the screen with his former copyright rival Superman.
6 Namor
Originally he had been created for a giveaway comic to Motion Picture Funnies Weekly for Funnies Inc. but it never ended up being published. Namor then appeared in Marvel Comics #1 for Timely Comics. He had many adventures through the 40s but would disappear. In the 50s he was briefly revived for Atlas Comics but wouldn't stick around long.
In 1962, he would reappear in Marvel Comics in Fantastic Four #4. Timely and Atlas comics were previous names for the company that would eventually become Marvel. After his debut in the Fantastic Four, he would become a big presence in the Marvel Universe for some time.
5 Blue Beetle
The Blue Beetle character originally started at Fox Comics. Dan Garret appeared in Mystery Men Comics #1 as a rookie cop who fought crime under the title of the Blue Beetle. Later it was revealed he had superpowers due to a mysterious scarab. After Fox Comics went out of business they sold the character to Charlton Comics. The character then passed the heroic identity to an apprentice in the form of Ted Kord.
After Charlton ceased publishing superhero comics, DC bought characters such as Blue Beetle, Captain Atom, and The Question. Originally these characters were slated to be used in a new comic limited series by Alan Moore called Watchmen. DC decided they wanted to keep these characters to use in their superhero universe so new characters were created that resembled the Charlton heroes. Blue Beetle became a big character for the company and eventually, the identity was again passed to a new character after Ted Kord was killed during Infinite Crisis.
4 Static Shock
Milestone Comics was created by a coalition of African American writers and artists to help promote more diversity in comics. They published through DC but were a separate company that DC had no editorial control over. While the line of comics was short-lived the character of Static had a popular cartoon show.
They started putting out comics in 1993 but ended their comic line in 1997 to focus on cartoons. In 2008 it was announced the characters from Milestone would merge into the DCU proper. Static seemed to be the character that got the most attention during this time as he joined the Teen Titans.
3 Angela
Back in 1993, Todd McFarlane hired a few writers to craft stories for his Spawn comic. One of those was Neil Gaiman who created Angela as an angel who came into direct conflict with Spawn and tried to kill him. During the debacle with Miracleman, Gaiman decided he wanted his ownership of Angela. He sued McFarlane and won the case.
After gaining the rights to Angela he immediately turned around and sold her outright to Marvel. It was revealed during the event Original Sin that she was actually the daughter of Odin and was Thor's sister. She has since been a member of The Guardians Of The Galaxy and had even led her own team in Strikeforce.
2 Wildstorm
While DC has bought other comic companies before and integrated their characters into their universe before Wildstorm was still actively publishing alongside DC as an imprint. Jim Lee brought his studio over to DC and they remained separate for quite a while. In 2010 all the titles under the Wildstorm banner wrapped up and the imprint officially closed.
DC then announced in 2011 they would be rebooting its universe with the New 52 and that the Wildstorm Characters would be brought over into the new revamped comics world. Grifter got his own series and some members of Gen 13 joined The Ravagers, which was a splinter group of Teen Titans.
1 Captain America
Cap shares a past similar to Namor. He first appeared at Timely Comics with his own series. After 10 years of stories, the title was canceled but in 1953 Atlas Comics tried to bring him back. It was a commercial failure as people didn't want to be reminded of World War II and superheroes were out of style. In 1963 the superhero team The Avengers was put together and in Issue #4 Captain America was discovered in a block of ice. He was revived and joined Marvel Comics and has never looked back.