AbiWord - AbiWord is a free software word processor.
Scrivener - Scrivener is a content-generation tool for composing and structuring documents.
LibreOffice - Writer - Open-source cross-platform word processor.
Final Draft - Use your creative energy to focus on the content; let Final Draft take care of the style.
Zoho Writer - Create. Review. Distribute
yWriter - Free writing software designed by the author of the Hal Spacejock and Hal Junior series. yWriter6 helps you write a book by organising chapters, scenes, characters and locations in an easy-to-use interface.