Mellel - Home Page for Mellel: The word processor of choice for scholars, writers and long document writing. for Mac OS X and iOS.
LibreOffice - Writer - Open-source cross-platform word processor.
Pages - Pages for Mac is a word processor that offers tools needed to create documents.
Microsoft Word - Microsoft Word is a commercial word document processor for Windows.
Scrivener - Scrivener is a content-generation tool for composing and structuring documents.
Google Docs - Create a new document and edit with others at the same time -- from your computer, phone or tablet. Get stuff done with or without an internet connection. Use Docs to edit Word files. Free from Google.