Okular - Okular is a universal document viewer based developed by KDE.
Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
calibre - Ebook manager, viewer & converter
Foxit Reader - Foxit Reader is a free and light-weight multi-platform PDF document viewer.
Haihaisoft PDF Reader - Haihaisoft PDF Reader is the name of a free to use PDF reader and printer that is extremely simple to launch.
Atril - Atril is a simple multi-page document viewer. Atril is a fork of Evince.