They’re also particularly useful for new writers who want to build a habit of writing every day but are unsure of what to write about.
The New York Times has a specific list of writing prompts for narrative and personal fiction.
The Story Shack offers a useful writing prompt generator for fiction writers.
Reddit has a comprehensive forum packed full of free writing prompts, with a heavy emphasis on fiction writing.
These are a set of cards or prompts for musicians, but they can be used for all types of creative work.