ODF Viewer - AndroidODF is a tool for viewing text documents, presentations and spreadsheets in ODF format for...
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.
LibreOffice Viewer - The Document Foundation provides a LibreOffice Viewer for Android.
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
Wondershare PDFelement - All-in-one PDF editor