pseudonym
A fake name a person uses instead of their real name.
A pseudonym is a fake name that someone uses instead of their real name, usually for writing or performing. The word comes from Greek roots meaning “false name.”
Many authors use pseudonyms when they publish their work. Samuel Clemens wrote his famous books about Tom Sawyer and Huckleberry Finn under the pseudonym Mark Twain. Eric Blair published his novel 1984 as George Orwell. Some authors choose pseudonyms because their real names are hard to pronounce or remember. Others want to keep their writing separate from other parts of their lives, or they want the freedom to write in different styles without confusing their readers.
A pseudonym differs from a nickname. A nickname is something others call you casually, like calling Margaret “Maggie.” A pseudonym is a deliberate choice you make to present yourself differently to the world, often professionally.
Musicians sometimes perform under pseudonyms called stage names. Actors might do the same with screen names. The key element is that you're choosing this name yourself for a specific purpose, not that someone gave it to you.
When someone uses a pseudonym, they might keep their real identity secret, or everyone might know both names. Either way, the pseudonym becomes the name the public knows them and their work by.