The phrase "a background character" is correct and usable in written English.
It can be used to refer to a character in a story, film, or play who has a minor role and does not significantly impact the main plot.
Example: "In the movie, the protagonist's friend is just a background character, providing support but not driving the story forward."
Alternatives: "a minor character" or "a supporting character".
Mr. Kenny seems to be pulling back a bit: taped shows in the future will have weather as a "main character," he said, not just a background character.
He wrote with sympathy and perception here about love and grief, finding it impossible to pass over a scene without allowing a background character a moment of yearning, or without insisting on offering a dramatic background to his minor figures.
Frank Mackey, the main cop in the third book, Faithful Place, is a background character in the fifth title, the echoingly named The Secret Place; and, in another example of this reprise technique, Frank's daughter, Holly, a nine-year-old witness in the earlier book, has become a 16-year-old suspect by the later one.
More common is noticing, as I did the other day, that every one of Miley Cyrus's VMA costume changes looked like a background character in gonzo cyberpunk comic Transmetropolitan – or, if you're not familiar with that masterpiece, basically any 1970s science fiction movie.
Benicio del Toro appeared in the video as a background character.
In early drafts of Final Fantasy VII, Tifa was to be a background character.
At the conclusion of the first season, one of the show's animators confirmed that "Derpy" would be a scripted background character in the second season, and was a part of several sight gags.
It is the fault of the screenplay that Yuezhen remains a sketchy background character.
The voice of SpongeBob was originally used by Kenny for a minor background character in Rocko's Modern Life.
The series would focus more on "coming-of-age issues", in a similar style to Buffy the Vampire Slayer, Dawson's Creek, and Smallville, with Jason as more of a recurring "background" character.
In 1998, the court told trial judges who were weighing a bid for leniency at sentencing after a three-strikes conviction that they could consider whether a defendant's "background, character and prospects" place him outside the "spirit" of three strikes.
