Movies/TV with characters that aren't in the source material.

Miss Tessmacher from Superman the Movie.

Black Vulcan was invented for the Superfriends and wasn’t a DC Comics character. Also Wendy, Marvin and Wonderdog. And the Wondertwins were introduced in the TV show before their debut in the comics.

Got anymore?

Oooh! I have one! Jessica, teenage vampire, on True Blood. She, and her whole story, were made up for the TV show. There are probably a lot more.

Harley Quinn was originally created for the Batman cartoons, but worked so well that they put her into the comics.

Ros the Exposition Whore from Game of Thrones.

There probably ought to be some spoiler protection somewhere in this thread, but there’s one obvious one that comes to mind- Ros the hooker in Game of Thrones is nowhere to be found in the books, and neither is Talisa the healer chick that’s seducing Robb Stark.

Is that Lex Luthor’s moll, as portrayed by Valerie Perrine?

Klinger in MAS*H.

Talisa is basically Jeyne Westerling. I don’t really understand why they changed her name and station (?) For the series, but she’s essentially Jeyne.

Inspector William Henderson was first in the 1940s radio version of “Superman” and then in the 1950s “Adventures of Superman” TV series. He didn’t appear in the original source, comics, until 1974

Yeah. Wikipedia has it spelled Teschmacher.

Chloe Sullivan and Pete on Smallville.

Pete was in the comics first.

Wybie from the movie “Coraline” does not appear in the book.

The BBC’s Sherlock has featured many characters from the original stories–updated for the 21st century. Sherlock & John–now on a first name basis with each other. Plus brother Mycroft, Inspector Lestrade, Mrs Hudson, the notorious Irene Adler–and Moriarty!

In the pilot, Louise Brealey had a small part as Molly Hooper, the patholotist/morgue attendant with a crush on Sherlock. ACD tells us that Holmes had beaten corpses in the morgue to gather evidence; surely, none of the attendants would have been female! The showrunners liked her & have used her in both series. In the last episode, she appears to have played a part in Sherlock’s miraculous escape…

The main characters of Haven were not in The Colorado Kid. Minor characters on the show similar to the main characters of the short story were, however.

How about the main (fully human) characters of Silent Hill? I remember hearing that the movie isn’t based on any of the games specifically.

I’ve been recently re-reading the Dorothy Sayers’ mystery, Five Red Herrings and thinking about the TV version done in the '70s with Ian Carmichael as Peter Wimsey. The TV version introduces a teenaged girl, a niece of one of the suspects who helps Wimsey with his investigation–a role reminiscent of Hillary Thorpe in The Nine Tailors. There is no character like this in the book; the nearest would be a much younger girl, the daughter of the same suspect, who appears in one scene but takes no greater part in the story.

In the animated adaptation of Watership Down, there’s a doe rabbit named Violet whose sole purpose is to be caught by a hawk about 15 minutes in (presumably to impress the viewer with the dangers of their journey). It’s not a big deal but it seems sort of pointless since they’re in danger soon enough anyway and detracts from the later point in the novel that the group who set out to start a new rabbit warren was all males.

Also, Colonel Potter, BJ, Charles, Nurse Kellye, Igor, Rizzo, Zale, Sidney Freedman, Col. Flagg, and Donald Penobscot.

They kinda had to do something, as this is the weakest of the novels, and needed something extra.

Similary, Jimmy Olsen first appeared on radio before comics. The same with kryptonite.