The Elements of Style
In this slim volume--considered by many the definitive guide to prose style--Strunk lays out the basics rules of grammar and punctuation, and the principles of composition applicable to most any writing. "The Elements of Style" belongs within ready reach of anyone who writes regularly.
The Only Grammar Book You'll Ever Need
While slightly larger than "Elements of Style," Thurman's book covers English grammar in greater detail without overwhelming the reader. Think of it as every English lesson you learned throughout high school (but may have forgotten), and condensed into 184 pages.
Story: substance, structure and style, and the principles of screenwriting
Written primarily for screenwriters, "Story" is useful to anyone writing narrative, regardless of genre. McKee's book is an exhaustive breakdown of dramatic storytelling, drawing from staples of Western mythology, classical Greek theater and contemporary filmmakers. This book is a virtual masterclass on how stories are made.
Dialogue: the art of verbal action for the page, stage, and screen
In his first follow up to "Story," McKee once again gives us a thorough breakdown of his subject, this time focused on a single component of dramatic narrative: dialogue. Written for storytellers of all genres--prose fiction, live theater and film--"Dialogue" further examines its subject's distinctions across those genres. Characters speak differently to one another on the page versus on the screen or stage, and "Dialogue" shows the reader exactly how and why.
The Art of Character: creating memorable characters for fiction, film and tv
Like "Story" and "Dialogue," David Corbett's "The Art of Character" addresses how writers create characters for multiple genres, with detailed examples from each. Like McKee, Corbett has written what is arguably the definitive book on how a writer creates the characters that propel a story.
On Writing: a memoir on the craft
A wonderful starting point for anyone confronting a blank page for the first time (or seasoned pros, for that matter), "On Writing" is half memoir and half style guide. In the first half, King recounts his evolution as a writer from his early years to the present; in the second half, he discusses in a concise and straightforward manner the basics of crafting good prose. While listed under the Narrative Theory heading, "On Writing" fits just as well beneath Prose Basics.
Steering the Craft
Le Guin, Ursula K.
A logical next step after King's book, "Steering the Craft" delves deeper into the later subjects of "On Writing." Additionally, Le Guin offers practical advice on point of view, indirect narration, tone, and other topics not as readily grasped as verb conjugation or comma usage. Listed below Narrative Theory for its sheer scope, "Steering the Craft" would be at home anywhere on this list.