A script doctor is a writer or playwright hired by a film, television, or theatre production company to rewrite an existing script or improve specific aspects of it, including structure, characterization, dialogue, pacing, themes, and other elements.
[3] Script doctors generally do their work uncredited for a variety of commercial and artistic reasons.
[1][4][5][6] For instance, to receive credit under the Writers Guild of America screenwriting credit system requires a second screenwriter to contribute more than 50 percent of an original screenplay or 33 percent of an adaptation.
[3] As script doctors generally do not contribute enough to a screenplay to qualify to the guild, production companies are not compelled to provide them with credit.
Some script doctors will also work uncredited due to artistic reasons, including not wanting to be associated with projects which fail despite their intervention.