A script doctor, also called a script consultant,
 is a
screenwriter or playwright hired by a
television, or theatre production to rewrite an existing script or polish specific aspects of it, including structure, characterization, dialogue, pacing, theme, and other elements.
Script doctors generally do their work
uncredited, for a variety of commercial and artistic reasons.
 They are usually brought in for scripts that have almost been "green-lit",
 during the development and pre-production phases of a film, to address specific issues with the script, as identified by the financiers, production team, and cast.
Writers Guild of America screenwriting credit system, a screenwriter must contribute more than 50 percent of an original screenplay or 33 percent of an adaptation to receive credit.
 Uncredited screenwriters are not eligible to win the
Academy Award for Best Screenplay or the
Writers Guild of America Awards.